Patent Publication Number: US-RE37135-E

Title: Fully automatic energy efficient lighting control and method of making same

Description:
REFERENCE TO CROSS RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 07/619,794 filed Nov. 29, 1990, now U.S. Pat. No. 5,142,199 and entitled “ENERGY EFFICIENT INFRARED LIGHT SWITCH AND METHOD OF MAKING SAME”. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to lighting controls. More specifically, the present invention relates to a lighting control or light switch which is automatic and energy efficient and provides automatic control of at least one bank of lights within a room, for example by detecting doppler-shifted, ultrasonic waves reflected by persons entering into and moving within the room. 
     BACKGROUND OF THE INVENTION 
     Conservation of energy is a critical national and worldwide concern. Continuous lighting in empty rooms is an unnecessary waste of energy. Some state and local energy conservation/building codes require installation of two light switches in the construction or reconstruction of offices, each to control a different portion of the overhead lighting. The reasoning behind such requirements is that in the interest of energy conservation, employees and janitorial personnel may be offered the opportunity to use approximately one half of the light they would normally require in their day-to-day activities. Depending upon the amount of ambient light available, employees working in a room may select to use only one half of the available bank or banks of lights. 
     Further, employees may tailor their specific lighting needs to their activities and location in the room. For example, employees working in an area not receiving sufficient ambient light may require more artificial light, depending upon their specific activities. Similarly, employees located in an area receiving sufficient ambient light may require less artificial light. Utilizing office lighting effectively, such that only approximately fifty percent is sometimes used and only in occupied offices, results in substantial energy savings. In addition, for computer applications, it is advantageous to reduce the level of light to eliminate the glare on cathode ray tubes (CRT). Conventional manual switches are inefficient because they depend upon human judgment to turn all or only a portion of the lights on and off. Existing automatic wall switches have also proven to be inefficient. For example, currently available light switches or the like used in offices emit an ultrasonic wave into a room and detect motion of persons by sensing a doppler-shift in the reflected ultrasonic wave. The doppler-shift in the reflected wave is caused by persons moving within the room. 
     Typically, these ultrasonic light switches are preset to a sensitivity level such that a person moving anywhere within the room is detected. Because the preset sensitivity level for the reflected ultrasonic wave is fixed, a wall switch located adjacent an open door can detect persons moving outside the door and unnecessarily turn on the lights within the room. 
     Although a wall switch that turns lights on automatically is preferable in most instances, in some applications occupants prefer a manual option for activating lights. For example, in situations where a person enters the room for a very brief period of time, such as a secretary delivering papers, the lights do not need to be turned on. Another example is a situation in which there is adequate ambient light. 
     SUMMARY OF THE INVENTION 
     The present invention provides a light switch, preferably an ultrasonic light switch or the like for a lighting system which is automatic and energy efficient and alleviates the problems associated with prior light switches. The light switch comprises different settings which are preset by a user. 
     In one aspect of the invention, the light switch in an automatic mode is configured to automatically activate lights upon detecting motion of any type within a room. In accordance with this aspect, in an exemplary embodiment, the light switch is set to an initial sensitivity level so that only motion within a short range (also referred to as an initial detection range) from the light switch is detected. An ultrasonic transmitter transmits acoustic energy or an ultrasonic wave of predetermined frequency into the room and an ultrasonic receiver receives a doppler-shifted, ultrasonic reflected wave indicating motion within the room. 
     Once the light switch detects motion within the short range, it automatically adjusts to a higher sensitivity level so that it is able to detect motion anywhere within the room. After motion is no longer detected during a variable time delay, the light switch automatically turns the lights off and initiates a predetermined grace period during which the light switch maintains the higher sensitivity level and continues to detect motion anywhere within the room. If no motion is detected during the predetermined grace period, the light switch returns to its initial sensitivity, thereby reducing the detection range in order to detect only persons entering the room. 
     In the event the lights are turned off inadvertently, such as if a person remains motionless during the entire variable time delay period, the predetermined grace period advantageously allows an occupant to wave an arm or otherwise make simple motions anywhere within the room to turn the lights back on. 
     In another aspect of the invention, the lighting can be turned off manually while the light switch is in its automatic mode, in which case it remains at its high sensitivity level while there are occupants in the room. After no motion is detected during the variable time delay and the predetermined grace period, the automatic light switch resets to its “automatic on” state and returns to its initial sensitivity level. 
     In yet another aspect of the invention, in a manual mode, the light switch is activated manually. In its manual mode, the light switch is configured to keep the lights off until someone activates the light switch. The lights will automatically turn off upon not sensing motion during the entire variable time delay period. If the occupant makes a motion within the predetermined grace period, the lights will automatically turn back on. If no motion is sensed during the predetermined grace period, the wall switch must be manually reactivated. 
     In still another aspect of the invention, the light switch comprises a load control switch that causes the light switch to activate at least one bank of lights within a room. The light switch operates at various voltages including, but not limited to 120 and 277 volts. 
     In yet another aspect of the invention, the light switch comprises a three position bypass switch which is used in the rare event of product failure. The bypass switch has an “off” setting for deactivating the light switch and the lights, an “automatic” setting for normal use in which the lights are controlled by the light switch, and an “on” position for electrically bypassing the light switch and leaving the lights on. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A complete understanding of the present invention and the above and other features of the invention may be gained from a consideration of the following description of the preferred embodiments taken in conjunction with the accompanying drawings in which like reference numerals indicate like parts, and in which: 
     FIG. 1A is a front plan view of the exterior of an energy efficient infrared light switch in accordance with one embodiment; 
     FIG. 1B is a side plan view of the energy efficient infrared light switch; 
     FIG. 1C is a top plan view of the exterior of the energy efficient infrared light switch; 
     FIG. 2 is a schematic representation of the electric circuit for the energy efficient infrared light switch; 
     FIG. 3 is a schematic representation of the energy efficient infrared light system incorporating the switch detecting a computer operator in a room and activating at least one bank of available lights. 
     FIG. 4 is a schematic representation of an automatic and energy efficient lighting system or control in accordance with another embodiment of the present invention, showing a light switch, preset to an initial sensitivity level for detecting a person entering a room and activating all or a portion only of at least one bank of available lights; 
     FIG. 5 is a schematic representation of the automatic and energy efficient light system shown in FIG. 4, illustrating the light switch preset to a higher sensitivity level for detecting a person moving anywhere within the room; 
     FIG. 6 is a front plan view of an exterior housing or front case of the light switch shown in FIG. 4; 
     FIG. 7 is a side plan view of the exterior housing of the light switch shown in FIG. 6; 
     FIG. 8 is a front plan view of a circuit board of the light switch of the present invention; 
     FIG. 9A is a schematic representation of a portion of an electric circuit for the light switch of the present invention; and 
     FIG. 9B is a schematic representation of the remaining portion of the electric circuit for the light switch of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An energy efficient light switch, such as an infrared light switch in accordance with one embodiment, replaces an existing standard wall switch and consists of at least two infrared detectors which can provide the device with a sweep of 170° to 180° within a bounded area. The infrared light switch is preset by the user to selectively activate all, none or a portion of the lights activated by the switch using the three-position switch. Through the use of two passive infrared detectors, the energy received by those detectors is converted to signals which are then separately amplified, mixed and then jointly amplified. The mixed and amplified signal is sent to a window comparator which compares the amplified and mixed signals to two predetermined known voltage signals. If the received, amplified and mixed signal is greater than the high setpoint of the window comparator, or lower than the low setpoint of the window comparator, a signal indicator is initiated indicating motion detection. The dual power supply in conjunction with a push-pull circuit and latching relay, then selectively actuates all, none or a portion of the lamps available within the bounded area. 
     FIG. 1A is a front plan view of the exterior case  5  of the energy efficient infrared light switch  2 . The exterior case  5  has a light emitting diode (LED)  62  as a signal detection indicator. A three-position switch  64 , located upon the front of the exterior case  5 , facilitates the individual setting of the light efficient switch  2  to selectively activate all, none or a portion of the lights. The infrared detectors  66 ,  66 ′ can be seen beneath the surface of the casing  5  within a protective cover. A stylus groove  68  provides ornamental decoration, but more importantly, also facilitates the receipt of infrared energy from the bounded area under detection. The front surface  61  of the energy efficient infrared light switch  2  has a height indicated at L 2  and a width indicated at L 1 . In one exemplary configuration the front surface  61  is square in configuration and L 1  and L 2  are 4.25 inches each. 
     FIG. 1B is a side plan view of the exterior of the energy efficient infrared light switch  2 , where its front surface  61  is exposed to a room and its back surface  63  is fixably mounted to a wall or corner. An interfitting seal  74  joins the front faceplate portion  70  of the switch and its rear cover portion  72 . The stylus groove  68  can be seen inscribed upon the surface of the faceplate portion  70  where the three-position switch  64  is located above the light emitting diode  62 . As shown in FIG. 1B, infrared energy  25  strikes the surface of the infrared detector  66 . The energy efficient infrared light switch  2  is shown in this example as being mounted to the surface of a wall interior to the bounded area. 
     As can be seen clearly in FIG. 1C, the faceplate  70  is interconnected with an interfitting seal  74  to a portion of the rear cover  72 . The front surface  61  of the faceplate  70  faces the interior of a bounded area or room. The back surface  63  attaches or mounts to a wall or a corner within that bounded area. The field of view  17  or sweep range, in the illustrated embodiment using two detectors, is between 170° to 180°. Infrared energy is indicated at  25  as striking the detector  66 . As shown above the stylus groove  68 , this three position switch  64  is operable to allow the detector switch  2  to be set to activate all, none or one half of the lights. 
     Referring now to FIG. 2 the circuit  10  comprises a first infrared detector  12  and a second infrared detector  14  which are operable to provide a combined sweep range of 170° to 180°. This sweep range is sufficiently wide to facilitate detection within a bounded area. The front end or first amplifier  16  for the first detector  12  includes an operational amplifier which converts and amplifies the infrared energy  25  received by the first infrared detector  12 . The front end or first amplifier  18  for the second infrared detector  14  is also an operational amplifier and receives radiated infrared converted energy detected by the second infrared detector  14 . Resistors R 1  and R 6  both having a resistance value of 100 kΩ, are connected in series, respectively, with the first and second infrared detectors  12  and  14 . The first and second detectors  12  and  14 , respectively, are not active since they do not emit infrared energy which is then redetected upon its return to the system. Rather the detectors passively await the receipt of infrared energy  25  emitted from within the bounded area. The signals received by the passive detectors  12  and  14  are filtered through a resistant capacitance filter having a resistor  82  with a resistance value of 220 kΩ, a capacitor  144  having a capacitance value of, 0.022 μF and a third resistor  84  having a resistance value of 10 kΩ. 
     As shown in FIG. 2, the second infrared detector  14  also includes a second filtering system wherein a resistor  92  having a resistance value of 220 kΩ, a capacitor  152  having a capacitance value of 0.022 μF and a second resistor  94  having a resistance value of 10 kΩ, also serve to filter the received signal. 
     As shown in FIG. 2, the front end amplifier  16  for the first infrared detector  12  contains an operational amplifier and two capacitors  146  having a capacitance value of 10 μF, a capacitor  148  having a capacitance value of 0.01 μF and a resistor  86  having a resistance value of 2.7 MΩ. A parallel system, a front end amplifier  18  for the second infrared detector  14 , also contains capacitors  154  having a capacitance value of 10 μF, a capacitor  156  having a capacitance value of 0.01 μF, a resistor  96  having a resistance value of 2.7 MΩ, and a third capacitor  158  having a capacitance value of 10 μF. Operational amplifiers in both front end amplifiers  16  and  18  receive a bias voltage  44  from the dual power system  31 . 
     In FIG. 2, the signals that have been filtered and amplified individually, from the first and second infrared detectors  12  and  14 , are combined prior to entering the second amplification stage  20 . The signal enters a second operational amplifier and a resistive capacitance circuit, having a resistor  100  with a resistance value of 2.2 MΩ, a capacitor  160  having a capacitance value of 0.01 μF, and a second resistor  102  having a resistance value of 2.2 kΩ. Again, the operational amplifier of the second amplification stage  20  is driven by a voltage bias  44  which is received from the dual power supply  31 . 
     The twice-amplified, mixed, combined and received signal from the first and second infrared detectors  12  and  14 , respectively, finally enters a window comparator  22 , containing first and second comparator circuits  24  and  26 , respectively, which includes operational amplifiers and resistors  104 ,  106  and  108 , which have resistance values of 22 kΩ, 10 kΩ and 15 kΩ, respectively. The comparator circuit also includes two diodes,  180  and  182  which are both 1N4148 diodes. The double amplified signal is compared in a comparator circuit  22  to the setpoint voltages established by the voltage divider network of resistors  104 ,  106  and  108 . If the received, amplified signal is either greater than the high setpoint or lower than the low setpoint of the window comparator circuit  22 , the indicator detector, such as a light emitting diode (LED)  28 , is actuated to the “on” position demonstrating that infrared energy has been detected. The output signal from the comparator  22  after it illuminates the LED  28  when motion is detected, enters into a timing circuit  30  which includes a transistor  208 , a resistor  114  which has a resistance value of 100 Ω, a capacitor  164  which has a capacitance value of 100 μF, a resistor  116  which has a resistance value of 6.8 MΩ, a resistor  120  which has a resistance value of 100 Ω, a resistor  118  which has a resistance value of 100 kΩ, and three resistors,  122 ,  124  and  126 , having respective resistance values of 620 Ω, 10 kΩ and 3.9 kΩ. The timing circuit  30  provides a time delay for the detection of infrared energy variable between 30 seconds and 15 minutes, once the variable resistor  124  is set. 
     As shown in FIG. 2, the electrical circuit for the energy efficient switch includes a dual power supply circuit  31  which is activated by placing slide switch  218  into the center or automatic position. The power supply functions differently with the lights on than with the lights off. With the lights on, power is converted with the current transformer and full wave rectified with the bridge rectifier. When the lights are off, power is converted via a resistor and capacitor and then half wave rectified in the circuit  35 . The voltage is then preregulated in the circuit  37  and filtered with capacitor  38 . The voltage is then regulated with voltage regulator  40  which provides the circuitry with a maintained 5 VDC source and the bias voltage used by circuits  16 ,  18  and  20  and operational amplifiers  48  and  50 . 
     Load control switch  34 , which is a double pole, three position slide switch, is provided so that all, none or a portion of the lights are activated upon infrared energy detection. As shown in FIG. 2, power line  56 , which contains the DC voltage signal after it has been rectified, preregulated, and filtered, leaves the dual power supply circuit and enables the latching relay control circuit  52  to activate the control of the lights. 
     Operational amplifiers  48 ,  50  function as comparators driven from the timing circuit  30 , to provide a pulse to the latching relay through the latching relay control circuit  50 . Once the time delay period is over, the operational amplifiers  48  and  50  will change to the opposite state and cycle the relay contacts open, thereby turning the lights off. 
     FIG. 3 is a schematic representation of an energy efficient light system detecting a person operating a computer in a bounded area or room containing two banks of lights. A standard room  11  has first and second banks of lights  13  and  15 . In actual use, the lights are wired so that one half or approximately one half of the lights in each fixture are connected to each circuit and can be controlled independently. The switch  2  replaces the conventional single or dual toggle switch generally mounted into the wall proximate the door. A computer work station  19  is positioned within the field of view. The person  21  seated at the computer console emits infrared energy  25 , which is detected within the sweep view of the detector  2 . Upon infrared energy detection, the switch  2  either turns on the first bank of lights  13  or the second bank of lights  15  dependent upon the detection of the individual and the setting of the switch  2  to activate all, none or one half of the available lights. In the exemplary embodiment, the two detectors of the switch  2  provide a field of view of approximately 170°. 
     FIGS. 4 through 9B illustrate another embodiment of the present invention. FIGS. 4 and 5 illustrate generally a fully automatic and energy efficient lighting system comprising a light switch  150 , for example ultrasonic or the like, in accordance with another embodiment of the present invention, mounted adjacent a door  240 , of a room  220  or other such confined area. The embodiments illustrated herein merely exemplify the invention which may take forms different from the specific embodiments disclosed. The light switch  150  of the present invention replaces a standard wall mounted single or dual toggle switch. 
     In an automatic mode, the light switch  150  is preset by a user to an initial sensitivity level, at which it detects motion only within an initial limited range, indicated by curve  260 , and distance from the door  240 , indicated by D 1 . The initial limited range  260  is sufficient to detect a person  21  entering the room  220 , but not spurious movement outside the room  220 , and to turn on at least one bank of available lights. For illustration purposes, only two alternating banks of lights,  300 ,  320  are shown. Each light bank consists of all lamps, which are connected to a single lighting power circuit. The lights  300 ,  320  may be of any type, for example fluorescent or incandescent. 
     When the light switch  150  detects a person  21  entering into the initial limited range  260 , the light switch  150  is configured to automatically adjust to a higher sensitivity level, at which the light switch  150  detects motion within an expanded or extended range, beyond the initial limited range  260 , indicated at  260 ′. The expanded range  260 ′ preferably covers the entire room  220 . This higher sensitivity level can be varied as desired and is preset by a user when the light switch  150  is installed. The light switch  150  keeps the lights  300 ,  320  on for as long as it senses motion within the room  220 . When motion is no longer detected, such as when a person  21  leaves the room  220 , the lights  300 ,  320  are automatically turned off after a variable time delay anywhere less than 60 minutes which can be varied and preset by a user. In the illustrated embodiment, the time delay is variable anywhere from 30 seconds to 15 minutes. 
     After the lights  300 ,  320  have been turned off, there is a predetermined grace period anywhere less than 12 seconds, preferably 5 seconds, during which the light switch  150  continues to detect motion within the expanded range. This is an advantageous safety feature in instances where the lights  300 ,  320  turn off inadvertently because the person was not moving sufficiently to be detected during the variable time delay. During the predetermined grace period, a person can wave an arm or otherwise cause motion to be detected, anywhere within the room  220  to reactivate the lights  300 ,  320 . After the predetermined grace period, the light switch  150  resets to its initial low sensitivity level. The light switch  150  can be turned off manually in its automatic mode, in which case it automatically resets to its initial low sensitivity level following the variable time delay and the predetermined grace period if no motion is sensed during that time. 
     In an alternative manual mode, the light switch  150  can also be operated manually to turn the lights  300 ,  320  on and off. In its manual mode, when no motion is sensed, the light switch turns off the lights  300 ,  320  automatically and is configured to reactivate the lights automatically within the predetermined grace period only upon sensing motion. This is a safety feature because it saves a person from walking to and groping in the dark for the light switch  150  to reactivate the lights  300 ,  320  manually. 
     Referring now to FIG. 4, in the automatic mode the light switch  150 , preset to the limited detection range  260 , detects an individual entering the room  220  and activates at least one bank of lights from the two available banks  300 ,  320 , depending upon which one is connected thereto. The light switch  150  is connected between a power source  140  and the banks of lights  300 ,  320  by electrical lines  170 . The light switch  150  emits ultrasonic acoustic energy  28  into the room  220  at a predetermined frequency, preferably 25,000 Hz (Hertz). At the initial sensitivity level it only receives doppler-shifted reflected waves  280 ′ when a person  21  is within the initial detection range  260  or distance D 1  from the door  240 , preferably between one and five feet. 
     Referring now to FIG. 5, the light switch  150  is configured to automatically adjust its sensitivity level, once a person  21  moving within the limited detection range  260  is detected and all or a portion only of the lights  300 ,  320  are turned on. This second sensitivity level allows the light switch  150  to detect motion within an extended detection range, indicated by curve  260 ′, at locations within the room  220  which are remote from the light switch  150  and beyond the initial detection range  260  in order to keep the lights  300 ,  320  on. At the higher sensitivity level, the light switch  150  receives doppler-shifted reflected ultrasonic waves  280 ′ when a person  21  is within the expanded detection range  260 ′ or within a distance D 2  from the door  240 . In an exemplary embodiment, distance D 2  is preferably between five and twenty-five feet. Depending upon the size of the room  220 , the higher sensitivity level can be varied to detect persons at any distance. The detected motion may be as little as motion caused by a person writing or turning his or her head. 
     The light switch  150  is preset to keep the lights  300 ,  320  on as long as a doppler-shift is detected in the reflected ultrasonic waves  280 ′. The lights  300 ,  320  turn off when a person  21  leaves the room  220  and no more motion is detected during the variable time delay, preferably anywhere from 30 seconds to 15 minutes. The variable time delay is preset when the ultrasonic switch  150  is installed and may be varied by a user as desired. After the lights  300 ,  320  have been turned off, the light switch  150  continues to detect motion within the expanded range during the predetermined grace period. This is an advantageous safety feature in instances where the lights  300 ,  320  are turned off inadvertently because the person within the room  220  is not moving sufficiently to be detected during the variable time delay. During the predetermined grace period, a person can wave an arm or otherwise cause motion to be detected, anywhere within the room  220  to reactivate the lights  300 ,  320 . After the predetermined grace period, the light switch  150  resets to its initial low sensitivity level. 
     Referring now to FIG. 6, a touch sensitive control cover  440  can be manually operated by users to turn the lights  300 ,  320  (shown in FIGS. 1 and 2) on or off, when illumination is not desired or necessary. The touch sensitive control cover  440 , disposed on an exterior housing or front case  230  of the light switch  150 , is fabricated preferably from a medium impact plastic. 
     In the event the lights  300 ,  320 , are intentionally or manually turned off, while the light switch is in its automatic mode, for example, if a user wants to darken the room to view slides or for any other reason, the light switch remains at its higher sensitivity level in order to detect motion anywhere within the room while occupants are present. The light switch resets to “automatic on” returning to its initial sensitivity level after no motion is detected during the variable time delay and predetermined grace period. 
     In an alternative manual mode, the light switch  150  can also be operated manually to turn the lights  300 ,  320  on and off. In its manual mode, when no motion is sensed, the light switch turns off the lights automatically and is configured to reactivate the lights automatically within the predetermined grace period only. This is a safety feature because it saves a person from having to walk to the light switch  150  in the dark to reactivate the lights  300 ,  320 . After the predetermined grace period has lapsed which begins when the lights  300 ,  320  have been turned off, the light switch  150  resets to its initial low sensitivity level. 
     The light switch  150  has three settings which can be preselected by a user. First, a push button touch sensitive switch  1240  (shown in FIG. 9A) disposed under the control cover  440  can be manually operated. The lights  300 ,  320  are turned on and off by depressing the control cover  440  to contact the touch sensitive switch  1240 . Second, a dual position, load control switch  350  (shown in FIG. 8) is mounted under a load control switch cover  340 . The load control switch  350  is displaced between a left position and a right position, by a user, to preselect whether all or only a portion of the lights  300 ,  320  connected to the light switch  150  are activated. Third, an automatic or manual two position mode switch  1580  sets the light switch  150  in its “automatic” or “manual” mode. 
     Referring also to FIG. 8, a three position bypass switch  370  is located on a circuit board  540  housed within the exterior housing  230 . An actuator  360  of the bypass switch  370  protrudes beyond a peripheral edge  130  to facilitate manual positioning. A user can move the actuator  360  to an extreme left position, indicated at A, to turn off or deactivate the ultrasonic switch  150 , a center position, indicated at B, to set the switch  150  in its automatic mode, or an extreme right position, indicated at C, to bypass the ultrasonic switch  150  and turn on the lights in case of failure or for any other reason such as those discussed above. 
     As shown in FIG. 6, the exterior housing  230 , upon its front face  190 , has a motion detection indicator  460 , preferably a LED (light emitting diode), which lights up upon detecting motion. The motion detector indicator  460  is located on the exterior housing  230  between the touch sensitive control cover  440  and the two position load control switch  340 . The exterior housing  230  includes at least one transmitter vent  380 , preferably a plurality as shown in FIG. 6, through which ultrasonic waves  280  are emitted into the room  220 . The exterior housing  230  has at least one receiver vent  400 , preferably a plurality, through which the light switch  150  receives doppler-shifted reflected waves  280 ′ from the room  220 . 
     A stylus groove  420  over both transmitter and receiver vents  380 ,  400 , respectively, provides ornamental decoration to the exterior housing  230  but, more importantly, allows the ultrasonic waves  280  to be emitted and received within the room  220 . The stylus grooves  420  are inscribed upon the front surface  190  of the exterior housing  230 , adjacent touch sensitive switch control cover  440 . The exterior housing  230  of the light switch  150  has a suitable length, indicated at L 1  and a suitable width, indicated at L 2 . In an exemplary embodiment, the exterior housing  230  has a square configuration wherein L 1  and L 2  have equal dimensions, preferably approximately 4.25 inches. 
     Referring now to FIG. 7, the front surface  190  of the exterior housing  230  faces the room  220  and a back surface  250  is mounted to a wall. An interfitting seal  270  joins the front surface  190  and the back surface  250  of the exterior housing  230 . A cavity  480  accommodates a power supply board (not shown) and extends from the back surface  250  of exterior housing  230 . Power input supply wires  500  enter the cavity  480  and electrically connect the light switch  150  to the power supply  140  (shown in FIGS. 4 and 5) and the lights  300 ,  320 . The light switch  150  in the illustrated embodiment is operated at a supply voltage of preferably 120 volts or 277 volts. 
     Referring again to FIG. 8, an ultrasonic transmitter  580  and an ultrasonic receiver  600  are positioned upon opposing sides of the circuit board  540 . The ultrasonic transmitter  580  emits ultrasonic waves  280 , preferably at a frequency of 25,000 Hz, through the transmitter vent  380  (shown in FIG. 6) into the room  220 . The ultrasonic receiver  600  receives reflected waves  280 ′ from the room  220 . Movement is detected by detecting a doppler-shift in the reflected ultrasonic waves  280 ′ caused by persons moving within the room  220 . The initial sensitivity level  260  of the light switch  150  is preset by an entry sensitivity control  620  so that the light switch  150  initially detects movement only within a limited detection range  260 . As described above, the limited detection range  260  is between one to five feet so that the light switch  150  advantageously detects a person entering the room  220  without causing the light switch  150  to activate unnecessarily as a result of spurious motion occurring beyond that range. 
     An area sensitivity control  640  sets the higher detection sensitivity level and is preset to cause the light switch  150  to detect motion within the expanded detection range  260 ′ at a distance of preferably five feet and beyond within the room  220 . Area sensitivity control  640  enables the light switch  150  to detect motion within the room after a person  21  has traversed beyond the initial detection range  260 . Motion detection indicator  460  lights up when the lights  300 ,  320  are turned on, indicating that motion is detected. 
     In operation, the three position bypass switch  370  can be preset by a user in three distinct positions: “bypass off” position A, “bypass automatic” position B and “bypass on” position C, to determine if and how the lighting within the room  220  is activated. When the bypass switch  370  is in the “bypass off” position A, the light switch  150  does not turn on the lights  300 ,  320  automatically. When the bypass switch  370  is in the “automatic” position B, the lights  300 ,  320  connected to the switch  150  turn on automatically upon detecting motion within the initial detection range and turn off automatically upon sensing no motion during the variable time delay. When the switch  150  is in the “bypass on” position, the lights are turned on regardless of whether or not motion is detected. 
     The touch sensitive switch control cover  440  can be activated by a touch to turn the connected banks of lights  300 ,  320  on or off. The load control switch  350  which is a two position switch, can be preset by a user to manually or automatically activate, all or a portion of the banks of lights  300 ,  320  electrically connected to the light switch  150 . The load control switch  350  is set in a left position to turn a portion of the banks of lights  300 ,  320  on during automatic or manual activation. Likewise, it is set in a right position to turn on all of the banks of lights  300 ,  320  connected to the light switch  150 . 
     Referring now to FIG. 9A, a circuit  8000  of the light switch  150  comprises a preamplification circuit  820  having the ultrasonic receiver  600  which receives the doppler-shifted reflected ultrasonic waves  280 ′ caused by a person  21  moving within the room  220 . These doppler-shifted reflected ultrasonic waves  280 ′ are amplified and filtered before they are compared to the ultrasonic sound waves  280  emitted by the light switch  150 . A pull-up resistor  870 , having an exemplary resistance value of 33 kΩ, provides the bias voltage for the preamplifier stages. The receiver  600  is connected in series with a capacitor  890 , having an exemplary capacitance value of 0.01 μF, and is connected to the input of an amplifier  880 . 
     The amplifier  880  and an amplifier  900  amplify the reflected ultrasonic waves  280 ′ received by the receiver  600 . A feedback network  860  comprising a resistor  910 , a resistor  950  and a capacitor  930 , having exemplary resistance and capacitance values of 1 kΩ, 33 kΩ and 0.01 μF, respectively, support the amplifier  880 . A feedback network  920  including a resistor  780 , a resistor  970  and a capacitor  790 , having exemplary resistance and capacitance values of 33 kΩ, 200 kΩ and 0.01 μF, respectively, support the amplifier  900 . 
     An analog switch  940 , controlled by an input  770 , controls whether the amplified, received signals are connected to the remainder of the circuit  800 . The output of the analog switch  940  is connected to a low pass filter  960  including a resistor  840 , having an exemplary resistance value of 10 kΩ, and a capacitor  830 , having an exemplary capacitance value of 0.01 μF. The output of the low pass filter  960  is connected to the area sensitivity control  640 , preferably a variable resistor having an exemplary resistance value of anywhere between 10 kΩ and 500 kΩ. 
     In operation, the area sensitivity control  640  is set such that as its variable contact is set toward ground, no signal is output from the preamplifier circuit  820 . If the variable contact is set high, away from ground, a high preamplifier output  1000  connects to a bandpass circuit  1020 . The area sensitivity control  640  is set to cause the circuit  8000  to detect motion occurring within the entire room  220 . The bandpass circuit  1020  receives the preamplifier output  1000  from the area sensitivity control  640 , amplifies and filters the same, passing only the doppler-shift frequency characteristics of the reflected ultrasonic waves  280 ′. 
     A pull-up resistor  1010 , having an exemplary resistance value of 33 kΩ, provides the bias voltage for the bandpass circuit  1020 . A capacitor  990 , having an exemplary capacitance value of 2.2 μF, passes the preamplifier output  1000  into an amplifier  1040  of the bandpass circuit  1020 . The amplifier  1040  and an amplifier  1020  amplify the preamplifier output  1000 . Amplifier  1040  has a feedback network  2710  comprising a resistor  1050  and a capacitor  1030 , having exemplary resistance and capacitance values of 510 kΩ and 0.01 μF, respectively. Amplifier  1080  has a feedback network  1090  consisting of a resistor  1150 , having an exemplary resistance value of 6.2 kΩ, a capacitor  1170 , having an exemplary capacitance of 0.0068 μF, a capacitor  1270 , having an exemplary capacitance value of 0.1 μF and a resistor  1190 , having an exemplary resistance value of 3.3 MΩ. A resistor  1090 , and capacitors  1070  and  1110  of the bandpass circuit  1020  have exemplary resistance and capacitance values of 10 kΩ, 0.001 μF and 0.1 μF, respectively. 
     The entry sensitivity control  620  comprises a variable resistor  1060  having an exemplary resistance value of 50 kΩ. The variable resistor  1060  is used to preset the initial sensitivity level representative of the limited detection range  260 , for example, one to five feet within the room  220 . An analog switch  1130  connects the variable resistor  1060  in parallel with the feedback resistor  1050  when input  1130 a is logically high. A bandpass output  1100  carries the filtered, demodulated and amplified wave to a comparator circuit  1120 . 
     The comparator circuit  1120  compares the bandpass output signal  1100  to a predetermined second bias voltage  850  (VBIAS-2). The response time of the comparator circuit  1120  is preset by a resistor  1210 , a diode  1230 , a resistor  1250 , and a capacitor  1290 . The diode  1230  is preferably a 1N4148 diode, the resistor  1250  has an exemplary resistance value of 1 MΩ, the capacitor  1290  has an exemplary capacitance value of 2.2 μF. A resistor  1310  has an exemplary resistance value of 330 Ω. When the comparator output signal  1100  is high, indicating no detection of motion, an output  760  of a comparator  1140  is low. When the bandpass output signal  1100  is sufficiently low to discharge the capacitor  1290  to a value lower than the predetermined second bias voltage  850 , indicating detection of motion, the output  760  of the comparator  1140  is high, thereby resetting a timer circuit  1220 . The comparator output  760  is connected to an analog switch  1180  via a resistor  1310 , having an exemplary resistance value of 330 Ω, and an LED  1160  of any conventional type known to those skilled in the art. The analog switch  1180  has an input  1200  which is connected to the output of the toggle circuit  1260 . The LED  1160  serves as the motion detection indicator  460 . 
     The comparator output  760  from the comparator circuit  1120  is connected to the timer circuit  1220 . Comparator output  760  is connected via a resistor  1330 , having an exemplary resistance value of 2.2 kΩ. When motion is detected, a transistor  1450 , having an exemplary part number of 2N3904, turns on, which in turn charges a capacitor  1370 , which has an exemplary capacitance of 100 μF. 
     If motion is not detected, the transistor  1450  turns off and capacitor  1370 , having an exemplary capacitance of 100 μF discharges its stored electrical charge through a resistor  1350 , having an exemplary resistance of 6.8 MΩ. When the voltage is higher than the voltage set by a voltage divider comprised of a resistor  1430 , a variable resistor  1340  and a resistor  1440 , having exemplary resistance values of 6.8 kΩ, 10 kΩ, 510 Ω, respectively, an amplifier  1300  resets the grace timer circuit  1500 . The variable resistor  1340  adjusts the variable time delay between approximately 30 seconds and 15 minutes. The amplifier  1300  includes a hysteresis resistor having an exemplary resistance value of 100 kΩ. After the variable time delay period has elapsed with no motion being detected, the output of amplifier  1300  goes low, causing the grace timer circuit  1500  to reset, and discharges capacitor  1320 . 
     The timer circuit  1220  includes the push button touch sensitive switch  1240  in parallel with an inverter stage  1260  having two digital inverters. A resistor  1260 a, having an exemplary value of 10 kΩ, is connected between the input and the output of the inverter stage  1260 . If the output of the second inverter in series with a diode  1280 , having an exemplary part number of 1N4148, is low, a capacitor  1320 , having an exemplary capacitance value of 2.2 μF, is discharged through the diode  1280 . 
     The circuit  8000  activates the lights  300 ,  320  when both the output of the amplifier  1300  and the output of the inverter stage  1260  are high. If either output is low, the capacitor  1320  discharges and does not enable the lights  300 ,  320  to be turned on. The output of the amplifier  1300  is connected via a diode  1390 , having an exemplary part number 1N4148, to the capacitor  1320 , the diode  1280  and a resistor  1410 , having an exemplary resistance value of 10 kΩ. 
     A grace reset signal  1520  from the timer circuit  1220  is input to a grace timer circuit  1500 . The grace timer circuit  1500  includes a timing chip  1600 , preferably a  555  timer, which receives the grace reset signal  1520 , via a capacitor  1490 , having an exemplary capacitance value of 2.2 μF. The grace timer circuit  1500  maintains the sensitivity of the light switch  1500  to detect motion anywhere in the room for the predetermined grace period, which is approximately 5 seconds in this embodiment. A resistor  1470 , having an exemplary resistance value of 100 kΩ, is connected between the supply voltage and the capacitor  1490 . A resistor  1510 , having an exemplary resistance value of 510 kΩ, is connected between the capacitor  1490  and ground. A diode  1530 , having an exemplary part number 1N4148, is connected in parallel with the resistor  1470 . A resistor  1600 a, having an exemplary resistance value of 3.9 MΩ, is connected between the supply voltage and an input of the timing chip  1600 . A capacitor  1550 , having an exemplary capacitance value of 2.2 μF, is connected between the resistor  1600 a and ground. 
     An output of the timing chip  1600  is connected to a diode  1540 , having an exemplary part number 1N4148. The grace reset signal  1520  is connected to a diode  1570 , having an exemplary part number 1N4148. The outputs of the diode  1540  and the diode  1570  are connected together and are connected to the input of an inverter  1560 . A capacitor  1560 a, having an exemplary capacitance value of 2.2 μF, and a resistor  1560 b, having an exemplary resistance value of 220 kΩ, are connected in parallel between the input of the inverter  1560  and ground. The output of the inverter  1560  is connected via a resistor  1610 , having an exemplary resistance value of 33 kΩ, to the input  1130 a of the analog switch  1130 . A capacitor  1630 , having an exemplary capacitance value of 22 μF, is connected between the resistor  1610  and ground. 
     The output of the inverter  1560  is connected to the automatic or manual two position mode switch  1580  for setting the light switch  150  in its “automatic” or “manual” mode. An exemplary part number 1N4148, is connected between the output of the inverter  1560  and the “automatic” switch terminal. A resistor  1580 b, having an exemplary resistance value of 2.2 kΩ is connected between the output of the inverter  1560  and the base of a transistor  1580 c, having an exemplary part number 2N3904. The collector of the transistor  1580 c is connected to the “manual” switch terminal. The center terminal of the mode switch  1580  is connected to the input of the inverter stage  1260 . 
     In the “automatic” mode, while either of the outputs from the amplifier  1300  or the grace timer circuit remain high, the output of inverter  1560  is low. When the outputs of the amplifier  1300  and the grace timer circuit are both low, the output of the inverter  1560  goes high, causing the analog switch  1130  to turn on, resetting the switch  150  to the initial sensitivity setting. Also, when the inverter  1560  output goes high, the output of toggle circuit  1260  is forced high regardless of its present state. When in the “manual” mode, a high output from inverter  1560  turns on transistor  1580 c via resistor  1580 b thereby forcing the output of the toggle circuit  1260  to go low regardless of its present state. 
     Referring now to FIG. 9B, a relay control circuit  1360  controls two comparators  1380  and  1400  and push-pull circuits  1420  which turn the banks of lights  300 ,  320  on and off. A signal  2090  from the timer circuit  1220  is connected to an input of the comparator  1380 . The comparators  1380  and  1400  feed respective push-pull circuits  1420  through a resistor  1750 , a capacitor  1770 , a resistor  1790 , and a capacitor  1810 , respectively. Resistors  1750  and  1790  each have an exemplary resistance value of 1 kΩ, while capacitors  1770  and  1810  each have an exemplary capacitance value of 10 μF. Push-pull circuits  1420  include a resistor  1870  having an exemplary resistance value of 47 kΩ, a capacitor  1870 b having an exemplary capacitance value of 220 μF and four transistors  1870 c. In an exemplary embodiment, two of the four transistors are preferably part number 2N3904 and the other two are part number 2N3906. The output signals of the push-pull circuits  1420 , a relay open signal  1460  and a relay closed signal  1480 , activate a relay  2030  in a main power supply circuit  1720 . 
     A transmitter circuit  1620  utilizes a crystal controlled circuit  1640  to generate the ultrasonic waves  280  of preferably 25,000 Hz. The crystal controlled circuit  1640  includes a crystal  2110 , a capacitor  2140  and resistors  2120 ,  2130  and  2150 . Capacitor  2140  has an exemplary capacitance value of 22 pF, while resistors  2120 ,  2130  and  2150  have exemplary resistance values of 1 MΩ, 1 MΩ and 2.2 kΩ, respectively. The 25,000 Hz signal is emitted through the ultrasonic transmitter  580 . Push-pull circuits  1700 ,  1700 ′ each contain two transistors  1700 a which drive the ultrasonic transmitter  580 . One transistor has a part number 2N3904 and the other has a part number 2N3906. Inverters  1670 ,  1690  and  1710  each have exemplary part number  4069 . Resistors  1650  and  1730  have exemplary resistance values of 3.3 MΩ and 2.2 kΩ. 
     The main power supply circuit  1720  incorporates a voltage divider chain  1800 . The voltage divider chain  1800  divides the main voltage for the circuit, which is preferably 5 volts DC, into the two biasing voltages, VBIAS-1 and VBIAS-2. A voltage regulator  1760  is connected to filter capacitors  1740  and  1780 , each having exemplary capacitance values of 100 μF. The voltage regulator  1760  regulates the input voltage through voltage divider chain  1800 , which contains resistors  1820 ,  1840  and  1860 . Resistors  1820 ,  1840  and  1860  have exemplary resistance values of 10 kΩ, 3.3 kΩ and 10 kΩ, respectively. Capacitors  1890  and  1910  each have an exemplary capacitance value of 10 μF. 
     The main power supply circuit  1720  also includes the relay  2030 , driven by the push-pull circuit  1420 , which physically activates the lights  300 ,  320  on and off. LOAD2, indicated at  2080 , represents a lighting load connected to the circuit  8000 . LOAD2 is connected to the energy efficient load control switch  350 . A user presets the two position load control switch  350  to activate a portion, for example, half or all of the lighting loads connected to the light switch  150 . A first lighting load, LOAD1, indicated at  2070  is shown in the power supply board circuit  1920 . The three position bypass switch  370  is also preset by a user to set the light switch  150  in its automatic mode or to bypass the light switch  150  completely. 
     The power supply board circuit  1920  can be mounted to a separate circuit board within the ultrasonic switch  150 . The power supply board circuit  1920  contains two distinct power supply portions. Specifically, when the lights within the room have been activated, a first portion  1940  of the power supply board circuit  1920  provides power to the circuit  800 . The first portion incorporates step-up transformer  1980 , and a full wave rectifier  2000  comprising diodes each having exemplary part number 1N4005. Zener diode  2020 , having exemplary part number 1N4747, receives the rectified voltage from resistor  2050 , having an exemplary value of 100 Ω. The zener diode  2020  removes excess voltage from the rectified voltage output of rectifier  2000 . When the lights are not turned on, the power is generated through a second portion  1960  of the power supply board circuit  1920 , where the input voltage passes through resistor  1990 , having a value of 27 Ω at 2 watts, and capacitor  2010  having a capacitance value of 0.47 μF rated at 630 V. Half-wave rectification occurs when the voltage passes through diodes  2040  and  2060 , each having exemplary part number 1N4005. The zener diode  2020  again removes excess voltage from the voltage output of the half-wave rectifier. 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications can be made without departing from the invention in its broader aspects and therefore the appended claims are intended to cover all such changes and modifications as allowed in the true spirit and scope of the invention.