Abstract:
An apparatus periodically dispenses an air freshening substance from a pressurized container into a room. A device is provided to sense when the room is occupied, such as by detecting the light level in the room. The air freshening substance is dispensed more frequently when the room is being used than at other times. However, the dispensing continues even when the room is unoccupied to treat odors arising from objects permanently located in the room.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a formal application which claims priority of Provisional Patent Application No. 60/275,831, filed Mar. 14, 2001. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT:  
         [0002]    None  
         BACKGROUND OF THE INVENTION  
         [0003]    The present invention relates to aerosol air fresheners, and more particularly to apparatus for automatically dispensing an air freshening substance at controlled intervals.  
           [0004]    Air fresheners are commonly used to mask odors within bathrooms and other interior spaces. The air freshening substance may also chemically neutralize the odors. Devices have been developed to automatically dispense the air freshening substance.  
           [0005]    One common type of dispenser utilizes a scented liquid contained in a pressurized canister. The canister is mounted in a holder which includes a motor that periodically operates a valve on the canister to dispense the scented liquid into the environment. The motor is periodically activated by a timer. The timing period typically is fixed and cannot be varied to meet the needs of a particular room in which the dispenser is installed. As a consequence, a greater amount of scented liquid may be dispensed into a room with a mild odor problem, and an insufficient amount of the scented liquid may be dispensed in a room with more persistent odors.  
           [0006]    Furthermore, once installed and activated, the device dispenses the scented liquid at regular intervals until the air freshener becomes depleted. Thus if the room is not occupied for a long period of time, during which air freshening is not required, the scented liquid continues to be dispensed at the same rate as when the room is occupied. It is desirable to control the dispensing in relation to the occupancy or usage of the room in which the dispenser is located.  
           [0007]    It is also desirable to provide a mechanism which indicates to the user when the supply of scented liquid in the canister becomes depleted. Otherwise the user has to periodically open the dispenser housing and inspect the canister to determine depletion of the air freshening substance therein.  
         SUMMARY OF THE INVENTION  
         [0008]    An apparatus periodically discharges a quantity of the contents of a canister, for example an air freshening substance, into a room. The apparatus has a motor which drives a member that engages the canister to open a valve thereby allowing the contents of the canister to be discharged.  
           [0009]    A sensor responds to a characteristic of the room and produces a signal indicating that characteristic. The characteristic provides an indication of occupancy or usage of the room. In the preferred embodiment of the present apparatus, the sensor detects the magnitude of light within the room.  
           [0010]    A control circuit is connected to the sensor and the motor. An input device is provided which enables a user to designate a dispense interval specifying the frequency at which the contents of the canister are to be discharged into a room. The control circuit evaluates the signal from the sensor to determine whether the room is being used. For example if the magnitude of light within the room exceeds a threshold level, as occurs when the room lighting is on, a controller determines that the room is in use and occupied. The controller periodically activates the motor at intervals which correspond to the selected dispense interval when a determination is made that the room is being used, and at other times the controller periodically activates the motor at intervals which are longer than the dispense interval.  
           [0011]    Thus the contents of the canister are dispensed more frequently when the room is in use, than when it is unoccupied. Therefore, the contents of the canister are conserved for periods of room usage while still providing a degree of dispensing at other times. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an isometric view of an exemplary air freshener according to the present invention;  
         [0013]    [0013]FIG. 2 illustrates the interior of the air freshener;  
         [0014]    [0014]FIG. 3 is a schematic diagram of the control circuitry for the air freshener; and  
         [0015]    [0015]FIG. 4 is a flow chart depicting operation of the control circuitry. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    With initial reference to FIG. 1, an automatic air freshener dispenser  10  has a housing  12  with a flat rear cover that mounts against the wall of the room. The housing has a first aperture  14  through which an aerosol air freshening substance is dispensed and has a second aperture in which an indicator, such as a light emitting diode (LED)  16 , is mounted.  
         [0017]    [0017]FIG. 2 illustrates the components which are mounted on a frame  20  inside the housing  12 . A pressurized canister  22  of an air freshener liquid is removably received in the frame  20  and has an outlet nozzle  24  with an integral valve that extends into the first aperture  14  in the housing. The canister  22  is able to slide within the frame  20  toward and away from the first aperture, as will be described. FIG. 2 shows the normal, or non-dispensing, state of the air freshener dispenser.  
         [0018]    An electric motor  26  also is mounted on the frame  20  and has an output shaft that engages a plurality of gears  28  which couple the motor to an actuator cam  30 . The combination of the motor, the gears and the actuator cam form an actuator that engages the canister to open the valve. The motor  26  is electrically connected to a printed circuit board  32  attached to the frame  20  and receives power from one or more batteries (not visible) within the housing  12 . As will be described, when the motor  26  is energized, the plurality of gears rotationally drive the actuator cam  30  so that one of the lobes  31  on the cam presses against the interior end of the canister  22 . This causes the canister to slide within the frame  20  toward the first housing aperture  14  which compresses a bow spring  25  on the canister. As the canister  22  is pushed farther toward the first aperture  14  the valve of the outlet nozzle opens dispensing the freshening substance through the first aperture  14  in the housing  12 .  
         [0019]    With continued movement of the motor, the cam lobe  31  disengages from the end of the canister  12  allowing the canister to slide away from the first aperture  14  due to force from the compressed bow-spring  25 . This motion closes the valve of the outlet nozzle thereby terminating the emission of the air freshening substance. The control circuit on the printed circuit board  32  energizes the motor  26  for an interval of time that is sufficient for the actuator cam  30  to make one-half a revolution, resulting in one air freshener dispensing cycle.  
         [0020]    [0020]FIG. 3 illustrates the control circuit  40  which is mounted on printed circuit board  32 . A controller  42 , such as a conventional microcontroller, includes a microprocessor which executes a program stored in an internal memory. The memory also provides storage locations for data required by the air freshener operation. The controller  42  has input/output circuits for interfacing to external components of the control circuit  40 . As an alternative to a programmable controller, the control circuit  40  can be implemented by a custom integrated circuit that has logic circuitry for controlling operation of the air freshener.  
         [0021]    The controller  42  has a reset input connected to a reset switch  44  which when closed initializes execution of the control program. Other terminals of the controller  42  are connected to a light sensor  48  which produces an input signal indicative of the intensity of the ambient light within the room in which the air freshener dispenser  10  is located. This provides an occupancy sensing mechanism that denotes whether the room, such as a rest room, is being used and thus requires relatively frequent air freshening. That is, the controller  42  determines that the room is being used when the lights of the room are on, and determines that the room is not being used, or vacant, when the room lights are turned off.  
         [0022]    Other room usage sensing mechanisms can be utilized with the present control circuit  40 . For example, in the case of a bathroom, a switch can be mounted on the frame of the door into the room to provide an electrical signal each time the door is opened. The controller  42  can be programmed to measure the intervals between opening of the door and reach a conclusion that the room is not being actively used when the door has not been opened for a reasonably long period of time. A passive infrared radiation detector also can be used to sense the presence of people in the room.  
         [0023]    The controller  42  has an input connected to a mode selector  46  that determines whether the air freshening substance is dispensed constantly at the same interval or operates in a mode in which the level of light sensed by light sensor  48  determines the interval at which the air freshening substance is dispensed, as will be described. Three other controller inputs are connected to level switch  50  which has three positions that allow the user to select from among three different intervals that specify the frequency at which the air freshening substance is to be dispensed. For example, the three positions of the level switch can select among dispensing the air freshening substance once an hour, once every two hours, or once every three hours. Other intervals can be employed depending upon the potency of the air freshening substance.  
         [0024]    The controller  42  has outputs for driving the light emitting diode  16 . The preferred embodiment of the present invention utilizes a dual light emitting diode  16  formed with two diodes  52  and  54 , which are driven separately to emit red or green light, respectively. Another output of controller  42  is connected to the gate of a field effect transistor (FET)  56  that controls the application of electricity to the motor  26 .  
         [0025]    When the air freshener dispenser  10  is placed into use, a rear cover of the housing  12  is attached to a wall or other surface in a room. Such attachment may be by screws, an adhesive strip, or other suitable means. The user then inserts the batteries  45  (FIG. 3) into the dispenser, places a canister  22 , containing the scented material, into the frame  20 , and presses the reset button  44 . The reset button  44  is pressed each time the canister  22  is replaced and signals the controller that a new supply of air freshening substance has been inserted into the dispenser.  
         [0026]    The controller  42  executes a control program which is depicted by the flow chart in FIG. 4. The program commences at step  60 , where a determination is made whether the reset switch  44  has been pressed by the user. If that is the case, the program execution branches to step  62  where a software implemented use counter is reset to zero. This counter maintains a count of the number of dispensing cycles that occur and the count, which is stored in the controller memory, is reset when a new canister  22  of scented material is inserted into the dispenser. At step  63 , a routine is activated which periodically flashes the green LED  54  to provide an indication to the user that the dispenser is operating. Then at step  64 , the program execution delays for thirty seconds to allow the user to close the housing  12 . This delay prevents the user from being sprayed with air freshening substance. Upon the end of that delay, the motor  26  is activated at step  65  to spray the scented material from the canister  22  and demonstrate to the user that the dispenser  10  is operational. The use counter is incremented at step  66  to count the dispensing operation that just occurred. The program execution then jumps to step  74 .  
         [0027]    When the dispenser  10  is not found to have been reset at step  60 , the control program branches to step  68  at which the controller  42  senses the voltage level from the batteries  45  and determines whether the batteries are becoming depleted at step  70 . If the batteries are supplying a low voltage level, the dispenser is switched off at step  71  and then enters a sleep state at step  72 . The controller will wake-up from this sleep state when the reset switch  44  is pressed as happens after the batteries are replaced.  
         [0028]    When the voltage level is satisfactory, the program execution branches to step  74 , the input connected to mode selector  46  is read by the controller  42  to determine whether the dispenser is to operate in the constant mode or the usage based mode. The position of the mode selector  46  is indicated by the voltage level at that input. As noted previously, the usage based operation utilizes the light sensor  48  to determine whether the room is being used as indicated by the light level within the room. In that operating mode, the control program branches to step  76  at which the input from the light sensor  48  is read and compared to a predefined threshold level that designates a sufficient magnitude of light to conclude that the room is being used by people. For example, the lights in a rest room are turned off during periods when a building is unoccupied and frequent air freshening is not required.  
         [0029]    If the light level in the room is below the predefined threshold, the dispense interval is set at step  78  to a relatively long default period, for example four hours. This results in the dispenser emitting the air freshening substance once every four hours, so that some level of air freshening is maintained even during periods when the room is not occupied. As often is the case, odors can be emitted from objects that are in the room even when people are not present. The value determined for the dispense interval is stored in a designated location within the memory of the controller  42 .  
         [0030]    When either the switch  46  indicates the constant mode (i.e. dispenser operation regardless of room usage) or the room is determined to be in use in response to the light sensor at step  76 , the program execution reaches step  80 . At this juncture, the three inputs from the level switch  50  are read by the controller  42  to determine whether the dispenser is configured for the high, medium or low level of air freshening. As noted previously, each of these three levels of air freshening specify different frequencies at which the scented material is to be dispensed from the canister  22 . Therefore, at step  82 , the position of the level switch  50  is used to set the dispense interval which then is stored in memory. For example, the high setting may indicate that dispensing should occur once every hour, the medium setting once every two hours, and once every three hours for the low level setting.  
         [0031]    After the dispense interval has been defined at either step  78  or  82  in FIG. 4, the program execution advances to step  84  where the value of the use counter is read and compared to a predefined value, designated “X”, which corresponds to the number of dispensing cycles that can be obtained from the quantity of air freshening substance within the canister  22 . This number of dispensing cycles is dependent upon the volume of the canister  22  and the amount of air freshening substance that is dispensed during each operating cycle of the dispenser  10 . If the maximum number of dispensing cycles has occurred, the controller activates a routine which periodically flashes the red LED  52  at step  86 . This provides a visual indication to the user that the air freshening substance within canister  22  has become exhausted and that a new canister should be inserted into the dispenser  10 . The program then jumps to step  94  and enters the sleep state, bypassing the dispensing steps.  
         [0032]    While the value of the use counter is less than the predefined value “X”, the program execution branches to step  88  where the controller  42  turns on the FET  56  to activate the motor  26  for a predetermined period of time that is required to rotate actuator cam  30  one-half a revolution. The motion of the actuator cam  30  causes one of the lobes  31  to engage the inner end of the canister  22  and slide the canister toward the first aperture  14  compressing the bow spring  25 . This action also pushes the outlet nozzle  24  into the canister thereby opening the valve and dispensing air freshening substance into the room.  
         [0033]    As the actuator cam  30  continues to rotate, the lobe  31  moves past the end of the canister  22  allowing the force of the bow spring  25  to push the canister away from the first housing aperture  14 . This subsequent motion closes the canister valve and terminates the dispensing cycle of the air freshener. The actuator cam  30  continues to complete the one-half rotation. As noted, the amount of rotation of the actuator cam  30  during each dispensing cycle is determined by the length of time that the controller  42  activates the motor  26 . Should the actuator cam  30  not return to the off position shown in FIG. 2, the user upon replacing the cartridge  22  can manually return the cam to that position.  
         [0034]    At the completion of the dispensing cycle, the motor is turned off and the use counter is incremented at step  90 . The software timer is loaded with the dispense interval value at step  92  and begins decrementing to time another interval between dispensing operations. The program execution then enters the sleep state at step  94  during which power consumption is reduced by minimizing the functions that are active. The controller can awaken from the sleep state by either the reset switch  44  being pressed or upon expiration of the dispensing interval timer. Thus the control circuit  40  remains in the sleep state until the timer elapses at step  96  at which time the control program returns to step  60  to repeat the execution cycle.  
         [0035]    The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. For example, although the present invention has been described in the context of an air freshener, it can be applied to dispensers for other types of aerosol substances, such as an insect repellant as one example. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.