BACKGROUND OF INVENTION 
   The present invention pertains to automatic switches for controlling electrical appliances. Particularly, it is a smart switch called Occupant Counter Control Switch, or OCCS, which automatically turns on and off electrical appliances such as lights by capable of keeping track and displaying the number of occupants in a room via the process of counting up when detecting a person entering the room and counting down when detecting a person leaving the room. When the display shows the count number greater than zero, indicating the presence of occupant/occupants in the room, and insufficient ambient light is detected, the OCCS turns on the lights and constantly keeps them on as long as the room is occupied. When the count or display reaches zero as the last person exiting the room, the OCCS immediately turns off the lights. 
   With today high price of energy and air pollution are concerned, a smart switch such as OCCS will help saving energy in every household and will consequently help keeping the earth atmosphere less polluted. It will be very useful for the families having teenagers who tend to be careless about turning off the lights after leaving the room, or for the families having young children who, are not tall enough to reach the switch, need help from the adults to turn on or off the lights every time they entering or leaving a room. OCCS will automatically take care of turning on and off the lights for them. Parents will no longer concern of any light be left on unintentionally in the house to waste power and to generate heat that keeps air conditioning to run excessively to waste even more energy. Thereby, the present invention OCCS devotes to save energy and to offer convenience in daily life. 
   Most of the automatic switches in the prior arts, such as the U.S. Pat. No. 5,946,209, simply turn on the lights for a preset period of time when detecting a person&#39;s movement in the motion-detection zone of the PIR sensor. When the preset time expires, the lights are turned off until the PIR sensor detects another human motion to turn on the lights again for another preset time period. This becomes very annoying when a person in a room sits almost motionless during the time he/she reading the book and the lights suddenly turns off upon timing out. If prolong the preset time for the possibility of the PIR sensor to detect another human motion before time out, the lights will stay on too long a period of time from the moment the room is unoccupied; therefore, energy is wasted. Moreover, this mentioned prior art is not very useful for application in a room that has partitioned wall or object blocking the view of the PIR sensor. 
   Other prior invention, U.S. Pat. No. 5,374,854, offered some similar functions to those of the present invention OCCS but did not provide a means to allow manually change the count value and a means to display the figure of the count value. This becomes ambiguous when the automatic switch of this said prior art miscounts, caused by human, and there is no means for recognizing the erroneousness; for example, when a person inadvertently stands in front of the sensor for a conversation with someone and his movements mislead the automatic switch to count up or count down excessively. The result of these excessive counts would unexpectedly turn off the lights and would be very inconvenient for the occupants who had to get out of and then reenter into the room to restart a new count cycle for turning on the lights properly. For a quick solution, someone would have certainly depressed the provided button on this said prior art to manually turn on the lights instead; however, this solution defeats the purpose of having a switch operates automatically since the last person who leaving the room has to manually turn off the lights. But more than likely that no one minds to turn off the lights because no one knows for sure that he/she is the last person in the room. With the OCCS, someone just enters the correct number of occupants and the OCCS takes care of turning off the lights automatically upon the last person exiting the room. 
   To overcome the mentioned problems and to make ease of use, the preferred embodiment of the present invention OCCS provides the means to display the figure of the count that indicates the number of occupants in the room and the means to allow manually adjusting the count value; therefore, the user can visually acknowledge the erroneousness, accidentally caused by the user, and be able to easily correct the count by pressing the button on the OCCS. The provided digital display also associated with the provided two push buttons to serve other functions of fine-tuning. With the intention of saving energy, the said digital display is programmed such that no more than one segment of the digit is flashed at any time. Each segment of the digit is flashed quickly and sequentially making the whole digit appears solidly illuminated. 
   Another reason for this invention is of its economical benefit. Only one OCCS needed at the entrance of the main room that contains several partitioned rooms that share the same light source (see  FIG. 1 ), whereas the mentioned automatic switch of the prior art, whose sensor&#39;s view is blocked by the partitioned walls, must be installed in every partitioned room to control its own light source. 
   SUMMARY OF INVENTION 
   The object of the present invention is to provide a smart switch that turns on and off electrical appliances such as lights in a room automatically by intelligently keeping track the number of occupants in a room via the process of counting up or counting down upon detecting a person entering or exiting the room respectively. The present invention smart switch called Occupant Counter Control Switch, or OCCS for short, comprises of 24VDC and 5VDC power supplies (see  FIG. 3 ), a PIR human motion detector with vision restricted (see  FIG. 5 ), a photo sensor, an amplifier with band-pass filter circuit, a microprocessor, a digital display, a relay or triac to drive electrical appliances, and two push buttons: one for manually turning on and off the said relay and one for manually increasing or decreasing the count shown on the said display. Besides its main function of displaying the digit of the count number of occupants in the room, the said digital display also associates with the said two push buttons to serve other purposes such as for manually adjusting PIR sensor threshold, adjusting ambient light referent level, and activating sleep mode. The said vision-restricted PIR motion detector of the OCCS is assembled in such a way that allowing it to be adjusted freely to aim at any direction so that the OCCS can be mounted either on the right side or left side of the entrance of the room or can be aimed down to detect children. 
   To achieve the benefit of saving energy and offering convenience in daily life, OCCS is invented to operate in its own way that sets it apart from other automatic switches available in the market. Unlike the previous inventions of the prior arts, such as the U.S. Pat. Nos. 5,946,209 and 5,656,995, which turn off the lights unexpectedly upon the preset time expires while the room is occupied and do not turn off the lights until the preset time expires since the moment the room is unoccupied, the nature operation of the OCCS allows it to constantly keep the lights on as long as the room is occupied and to instantly switch off the lights upon the last person leaving the room. OCCS also provides a feature of sleep mode that is another convenience for the user when it is installed in the bedroom. 
   Comparing with the prior art U.S. Pat. No. 5,374,854, which offered similar functions to those of the OCCS, the present invention OCCS is more advanced in a way that it provides a digital display to show the count of the number of persons in a room and also provides the user a means for easily change the count value when the user accidentally causes the device, OCCS, to miscount that interrupts the lights. The present invention OCCS is simpler to build and less expensive; therefore, it will be more affordable for the public. 


   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  shows the OCCS (Occupant Counter Control Switch) mounted at the entrance of the main room that contains a partitioned room. The OCCS has automatically turned on the light since detecting the first person (the lady speaking on the phone behind the partitioned wall) walked into the room. The OCCS displays a number “2” as it detects the second person (the man) entering the room and it constantly keeps the light on as long as the room is occupied. 
       FIG. 2A  shows the front view of the OCCS consisting of:  1 _The cover plate;  2 _The removable dome shape Fresnel lens that covers the vision-restricted PIR sensor, the Photo sensor and the screw;  3 _The screw;  4 _The adjustable vision-restricted PIR sensor;  5 _The Photocell sensor;  6 _The digital display;  7 _The Counter Up/down soft push button;  8 _The OnOff/Sleep soft push button. 
       FIG. 2B  shows the side view of the OCCS with additional item  9 , the electrical enclosure piggybacks to the cover plate; item  10 , the PIR signal wires; item  11 , the pivot-join supporter that, can be rotated 360 degree along its shaft, supports the vision-restricted PIR sensor. 
       FIG. 3  shows the block diagram of the OCCS circuit consisting of:  12 _The 24VDC unregulated power supply that energizes the relay and the 5VDC supply;  13 _The regulated 5VDC power supply that provides power for electronic components;  14 _The PIR sensor;  15 _The PIR amplifier with band-pass filter;  16 _The photocell sensor circuit;  17 _The microprocessor chip;  18 _The relay to drive electrical load;  80 _The seven-segment LED display;  19 _The electrical load;  20 _The OnOff/Sleep soft touch push button;  21 _The Counter Up/Down soft touch push button. 
       FIGS. 4A and 4B  show the amplitude in volts versus time in seconds of the Enter waveform and Exit waveform of the PIR sensor signals consisting of: U_the upper pulse; L_the lower pulse; R_the residual pulse. The pulse widths of these waveforms vary with the walking speed of a person passing through the PIR sensor. 
       FIG. 5A  shows the PIR sensor being encapsulated in a cylinder tube to narrow its detection angle. The figure consists of:  22 _the restrict-vision tube;  23 _the PIR sensor body;  24 _the Exit element sensor;  25 _the Enter element sensor. 
       FIG. 5B  shows the defined vision angle of the vision restricted PIR sensor. The figure consists of:  74 _the restrict-vision tube length Y;  24 _the Exit element sensor;  25 _the Enter element sensor;  26 _the vision angle Alpha that is defined as Tan(alpha)=X/Y. Where Y is the length of the restrict-vision tube and X is the radius of the tube plus 1 mm. Length Y is proportional to the PIR signal gain. 
       FIG. 6  shows the circuit diagram of the Occupant Counter Control Switch. 
       FIG. 7  shows the algorithm of the program embedded in the microprocessor that directs the operation of the Occupant Counter Control Switch. See detail in the Detailed Description 
       FIG. 8  shows the Vision-Restricted PIR Sensor mounted on the pivot-join supporter. The figure consists of:  75 _the restricting PIR sensor vision tube;  76 _the encapsulated PIR sensor;  77 _the PIR signal wires;  78 _the Pivot-join supporter;  79 _the Cover Plate. The restricting vision tube and the PIR sensor as a whole can swing 180 degree on the Pivot-join supporter. The Pivot-join supporter is connected perpendicular to the Cover Plate and can be rotated around its axis but limited to 360 degree to prevent the PIR signal wires from excessively twisting. 
   


   DETAILED DESCRIPTION 
   As shown in the  FIG. 3 , the present invention Occupant Counter Control Switch, OCCS for short, is provided with a PIR motion sensor  14  to detect heat, infrared energy, from human body moving across the sensor. The PIR sensor is powered by a regulated 5VDC  13 , which is supplied by an unregulated 24VDC  12 . The signal of the PIR sensor is, unique to each of the two directions of a person entering or exiting the room (see  FIG. 4 ), amplified and filtered by U 2  with the RC combinational network R 10 , R 11 , C 5 , C 6 , and C 7  shown in the  FIG. 6 . U 2  is bias at 2.5VDC and is in current amplification mode. The amplified PIR signal is then fed to the A/D, analog to digital converter, of the microprocessor U 4  in  FIG. 6  for further process for counting and thereby controlling the relay to drive electrical appliances. The embedded program, based on the algorithm shown in  FIG. 7  that will be clarified later, directs the microprocessor from receiving and analyzing inputs to appropriately timing and logically sequencing to ensure the proper arranging and selecting of events that lead to the right outcome among the outputs. The microprocessor provides seven outputs to drive seven LED segments of the digital display  80  (see  FIG. 3  and  FIG. 6 ). Each segment of the digital display is blinked at a time and the embedded program controls the sequence of blinking rapidly such that the display of the entire digit appears solidly illuminated. The Photo sensor circuit  16  (see  FIG. 3 ), also powered by 5VDC, feeds its signal to another A/D input of the microprocessor to prevent the relay from closing if adequate ambient light is detected. The relay  18 , driven by an operational amplifier that powered by 24VDC, receives command from the microprocessor to turn on or off the electrical load. The push button  20 , tied to an input of the microprocessor, serves as a manual on off toggle switch when it is released after being pressed and held in shorter than half a second, and serves to activate sleep mode when it is released after being pressed and held in longer than half a second. The push button  20  also servers as a manual single count up from zero to one upon it is released after being pressed and held in less than half a second when the count or the shown display is at zero; this is a convenient feature that allows the user to turn on the lights by pressing any of the buttons when the count is at zero. The push button  21 , tied to another input of the microprocessor, is for manually adjusting counting up or down. The counter counts up when the button  21  is released after being pressed and held in longer than half a second. The counter counts down when the button  21  is released after being pressed and held in less than half a second. The push buttons are assembled with the overlaid rectangular plastic pieces whose areas are big enough to allow easily getting pressed (see  FIG. 2A ). 
   When the two buttons together are pressed and released, the system enters into adjusting mode and the display shows a letter “A” to mean adjusting. The letter “A” will soon change into a digit, the level, of adjusting when one of the buttons is pressed. There are nine levels in each adjusting mode. In PIR sensor adjusting mode, the push button  20  is for increasing or decreasing the sensitivity of the PIR sensor to extend or reduce the detection range respectively. To decrease the sensitivity, the button  20  must be pressed and held in longer than half a second. To increase the sensitivity, the button  20  must be pressed and held in shorter than half a second. In lighting demand adjusting mode, the push button  21  is for changing the photo sensor reference, that is called the lighting demand level, which is compared with the photo sensor digitized voltage. When released after being pressed and held in longer than half a second, the button  21  increases the lighting demand level. If the lighting demand level is adjusted higher than that of the current ambient light and the count is greater than zero and the said relay has not been manually turned off, the lights is allowed to automatically turn on. To decrease the lighting demand level, the button  21  is pressed and held in less than half a second. If no more pressing on any button for about one minute or the two buttons are pressed and released together, the system will get out of the adjusting mode and resume its normal operation. 
   Shown in the  FIG. 7  is the control algorithm of the embedded program that directs the said microprocessor to perform its functions. After power up, the microprocessor initializes all values of variables and constants and then stays within the main loop starting at block  27 . The microprocessor reads the status of the PIR sensor block  28  and quickly blinks a segment of the displayed digit zero block  29 . If the PIR sensor detects a person entering the room, its amplified signal rises above the bias level 2.5V denoted as U-pulse (upper pulse) in block  30 . As the person continues passing through the PIR sensor, his/her body infrared energy strikes the other sensor element that causes the signal falling, resulting from the negative charge of the latter element, below 2.5V denoted as L-pulse (lower pulse) in block  34  (also see  FIG. 4A ). In the case if noise affects the PIR sensor and causes the U-pulse to occur without the immediate following of the L-pulse block  34 , the program loops back to start a new cycle at block  27 . Noise is usually caused by a person walks near by the sensor. Now if the presence of the L-pulse  34  after the U-pulse  30 , counting up takes place block  39  and the microprocessor also quickly blinks another segment of the display. The count now is greater than zero and the program reads the photo sensor status  42  and also quickly blinks another segment of the display block  43 . If the photo sensor detects insufficient ambient light  44 , then logically the lights or lamps should be turned on, which is true in  47  if the relay was not manually turned off in  46 . If the relay was manually turned off in block  46 , the lights are not allowed to be on via block  40 ; another segment is also blinked at this point. On other hand, if enough ambient light is detected in  44 , then logically the lights should not be on, which is true in block  40  if the relay was not manually turned on in  45 . However, if the relay was manually turned on in  45 , the lights must be on by block  47 . Another segment of the display is also blinked and the program loops back to start  27  for a new cycle. A similar logic is applied for detecting a person exiting the room, which is when the L-pulse  31  occurs first and the U-pulse  35  immediately follows (also see  FIG. 4B ). The residue pulses shown in  FIGS. 4A and 4B  are ignored as noises. The counter now is counting down in block  38  and following is another blink of the segment. If the count reaches zero in block  41 , the lights are immediately turned off by block  40  and the program starts another new cycle. If the count is still greater than zero, the outcome of the lights is dependent on the combination of ambient light and manual control the relay via the On/off toggle push button just as described above. 
   If no activities from the PIR sensor after start of a cycle, the program checks the count push button, Cnt-Swt in block  32 . If the count button is pushed and held in longer than half a second in block  36 , the counter counts up in block  37  as the count button is released and another segment of the display is also blinked. The counter now is greater than zero and the program follows the same path from block  42  as described above to determine the outcome of the lights. The counter counts down in  38  if the count button is released after held in shorter than half a second. The count value is then checked in  41  to determine the status of the lights on or off by following the same path of blocks  40  or  42  just as described above. If no activities from the count button in block  32 , the program goes on to check the status of the On/off-Swt push button in block  33 . If the button is released after pushed and held in less than half a second in block  49 , the relay is energized in  47  to turn on the lights if the relay has not been energized before in block  48 . If the relay has been energized in block  48 , the lights are turned off via block  40  of de-energizing the relay. Thus, when the On/off button in block  33  is pushed and held in less than half a second, it serves as a toggle switch to turn the lights on or off. On other hand, if the same button in  33  is held in longer than half a second, the program triggers the sleep mode and displays the letter “L” in  50 . Letter “L” stands for “sleep”. The sleep mode is a timer interrupt mechanism that keeps the lights on a certain period of time, preset about three minutes, to allow the user getting prepare before getting into the bed. The interrupt mechanism causes the program frequently interrupts what it is doing to check on the timer in block  51  and then returns to where it interrupted to continue its routine. When the timer expires in block  51 , the lights are automatically switched off by block  69  to let the user sleeps. The sleep mode is either deactivated in block  66  by the On/off button in block  65  is pressed and held in less than half a second or by the count reaches zero in block  70  as the last person exits the room. 
   If the program finds no activities of the On/off button in block  33 , it moves on to check the Sleep Mode in block  68 . If the Sleep Mode is active, the lights have been off, the program checks on the On/off button again in block  65  and continues on as described above. If the Sleep Mode is not active in  68 , the program checks on both buttons, the On/off-Swt and the Cnt-Swt, in block  52 . If they both together are pressed, the program steers into adjusting mode and builds and blinks a segment of the letter “A” in  53  to indicate the system is in adjusting mode. Each segment of the letter “A” is rapidly blinked in  67  until the two buttons are released. The letter “A” will soon change into a digit that reflects the level of adjustment as one of the buttons is pressed. As the two buttons are released in  64 , the adjusting mode timing is set and is checked in  54 . If no more activities of the two buttons are detected until the adjusting mode time out, about one minute, in  54 , or the two buttons together are pressed again in  55  before adjusting mode time out, the program will get out of the adjusting mode and restart a new cycle. Once in the adjusting mode, before adjusting mode time out, if the On/off button in  56  is pressed and released after held in longer than half a second in  59 , the photo sensor reference is increased. There are nine levels of adjustment for the photo sensor reference. A segment of the digit, the level, of adjustment is blinked and a constant PTOconst is multiplied with this adjusted level in  60  to form a photo sensor reference product that will be compared with the ambient light level in the block  44 . The ambient light level is the voltage from the divider network formed by the photo sensor Pcell and R 12  in the  FIG. 6 . This voltage is digitized into counts and is compared with the photo sensor reference. The photo sensor reference is also called the lighting demand level. If the lighting demand level is higher than the level of the current ambient light in the room, the lights are allowed to automatically turn on after a change in count, that means when there is a person entering or exiting the room. Once the lights are on, the photo sensor is disabled to prevent the on and off oscillation of the lights. If the On/off button is pressed in  56  and released after held in less than half a second in  59 , the photo sensor reference or the lighting demand level is decreased in  61  and the program prevents the lights from automatically turning on if the lighting demand level is lower than the level of ambient light. Like the process in  60 , constant multiplication and blinking a digital segment take place in  61 . 
   If the program detects the count, Cnt-Swt, button is pressed in  57  while in the adjusting mode, the PIR noise immunity is adjusted. There are also nine levels of adjustment of the PIR noise immunity. When the count button is pressed and held in longer than half a second in  58 , the PIR noise immunity is increased in  62 . The noise immunity level is multiplied with the PIRconst constant to form a product that determines the signal sensitivity of the PIR sensor. A segment of the digit of the noise immunity level is also blinked in  62 . If the count button is held in less than half a second in  58 , the PIR noise immunity is decreased in  63  and the same process of constant multiplication and blink a segment also takes place. The PIR noise immunity is helpful in setting the detection range of the PIR. The lower the noise immunity level, the farther the detection range is, and vise versa. If no activity of the two push buttons is detected, the program keeps blinking sequentially each segment of the digital display in block  71  until the adjusting mode timer in  54  expires. After the processing  60  or  61  or  62  or  63 , the program checks the adjusting mode timing  54 . If the time is up, the program jumps out of the adjusting mode and restarts a new cycle. The adjusting mode timing will be set for one minute. The user can also terminate the adjusting mode by pressing both buttons together as mentioned in the block  55 .
A provided smart switch called Occupant Counter Control Switch, or OCCS, basically comprises of a motion sensor PIR, a photo sensor, an amplifier with band-pass filter, a microprocessor, a digital display, and a relay or triac to drive electrical appliances such as lights. The PIR sensor detects heat from a human body moving across it and generates a distinctive signal that is, unique to each of the two directions, further processed by the microprocessor for counting and thereby controlling the relay. Installed at the entrance of a room replacing the regular switch (see FIG. 1), the OCCS counts up, displaying a digit great than zero, upon detecting a person entering the room and turns on the lights if sensing insufficient ambient light. OCCS constantly energizes the lights during the room is occupied and immediately switches them off upon counting down to zero when detecting the last person exiting the room.