Abstract:
An actuating device including a load and an integrated electronic control circuit comprising a microcontroller and at least one passive component. The microcontroller performs the dual function of providing a control signal to generate sufficient power to actuate a load and a drive signal to drive the load.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an actuating device having an integrated electronic control circuit. More specifically, the present invention relates to an actuating device having an integrated electronic control circuit for driving a load and controlling voltage to power a load. 
   BACKGROUND OF THE INVENTION 
   Actuating devices are well known in the art. Typical actuating devices drive a load or an actuator. An actuator is a device that converts electrical energy to mechanical energy. Exemplary actuating devices include devices for generating liquid droplets of active materials, such as air freshening systems, air treatment devices, nebulizers; and mechanically operated toys. To drive a load or actuator, an actuating device requires a sufficient amount of power. For example, an electromechanical actuator that generates liquid droplets of perfume materials in an air freshening system typically requires at least about 200 mA, at various voltages such as about 100 volts. To generate multiple voltages from a single variable voltage, air freshening systems, for example, often utilize a direct current to direct current (DC/DC) converter. Additionally, para-medical actuating devices such as nebulizers typically utilize DC/DC converters for its reliability in providing continuous operation. A DC/DC converter is a circuit which converts a source of direct current from one voltage level to another. DC/DC converters offer a method of generating multiple controlled voltages from a single variable battery voltage, thereby saving space instead of using multiple batteries to supply different parts of the device and, in turn, enable continuous operation of an actuating device. As such, DC/DC converters are commonly utilized in hand held or portable actuating devices. However, the cost of a DC/DC converter may be half of the retail price of a portable household actuating device, such as an air treatment or air freshening system, which makes its application in household actuating devices cost prohibitive. Thus, there remains a need for an electronic control circuit that is cost appropriate for portable household applications. 
   SUMMARY OF THE INVENTION 
   The present invention relates to an actuating device comprising an actuator and an integrated electronic control circuit that includes a microcontroller and at least one passive component in electrical communication with the microcontroller. The integrated electronic control circuit is operatively associated with the actuator and the microcontroller provides a control signal to one of said at least one passive component for controlling a voltage that powers the actuator and provides a drive signal to drive the actuator. In this way, the present invention allows an actuating device to operate the foregoing two tasks reliably with one less application specific integrated circuit (ASIC) than the prior art circuits having a DC/DC converter. 
   In one embodiment of the present invention, the actuating device may be an air freshening system having an electromechanical transducer that may generate droplets of liquid active materials such as perfumes, other volatile liquids and/or volatile materials; and an integrated electronic drive circuit that includes a microcontroller and at least one passive component in electrical communication with the microcontroller for performing the dual functions of a controlling the voltage to power an electromechanical transducer, and providing the drive function that drives the electromechanical transducer. 
   The present invention also relates to a method of actuating a device comprising the steps of providing an actuator and an integrated electronic control circuit that includes a microcontroller and at least one passive component in electrical communication with the microcontroller; generating a drive signal from the microcontroller to drive the actuator; and generating a control signal from the microcontroller to control a voltage that powers the actuator 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While the specification concludes with the claims particularly pointing and distinctly claiming the invention, it is believed that the present invention will be better understood from the following description taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a block diagram of an exemplary electronic control circuit according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , the present invention comprises an integrated electronic control circuit  10 , a power supply  50  that supplies power to the integrated electronic control circuit  10 , an amplifier  60  that receives power from the integrated electronic control circuit  10  for powering a load  40 . The load  40  may be part of the integrated electronic control circuit  10 . An integrated electronic control circuit  1  is an electronic circuit that includes a microcontroller  20  and at least one passive component  30  in electrical communication with the microcontroller  20 . An integrated electronic control circuit  1  includes a microcontroller  20  that is capable of sending an electrical signal to a passive component  30  and is also capable of receiving an electrical signal from a passive component  30 . A passive component is an electrical building block that consumes energy but does not have an ASIC embedded therein. A DC/DC converter, for example, is not a passive component as it has an ASIC embedded therein such that sufficient power can be supplied to an actuating device. An electronic circuit consisting entirely of passive components is called a passive circuit and has the same properties as a passive component. 
   The microcontroller  20  may be programmed to provide the appropriate function for the desired circuit or alternatively, the microcontroller  20  may have a dedicated program embedded in ROM. The integrated electronic control circuit  10  according to the present invention may power an actuating device  1  without utilizing a DC/DC converter to control the voltage levels that are required to power a load  40 . The microcontroller  20  according to the present invention is configured to perform both tasks of driving the load  40  and controlling a voltage to provide sufficient power to actuate the load  40 , where both tasks can be performed more inexpensively than circuits using a DC/DC controller. 
   The present invention simplifies the electrical signals required to operate an actuating device  1 , because the information for the drive signal  122  and the control signal  124  are generated from a common microcontroller  20 , instead of a microcontroller requiring an input control signal from an electrical control circuit in which the microcontroller is not part of. Due to the integration of the microcontroller  20  with the passive elements  30 , the microcontroller  20  responds when the drive signal generator  22  generates a drive signal  122  to the amplifier  60  and is capable of counting clock cycles to respond when power is required by a load  40 . For purposes of illustrating the present invention in detail, the present invention will be described in an air freshening system for generating liquid droplets of perfume materials. The liquid material may be contained in a reservoir that is part of the device. The perfume materials may have a viscosity of about 3 to about 9 centipoise (cps), alternatively about 3 to about 5 cps, alternatively at least about 10 cps, and which have surface tensions below about 35 dynes per centimeter, alternatively in the range of from about 20 to about 30 dynes per centimeter. However, as stated above, those of ordinary skill in the art will understand that the present invention can be embodied in various actuating devices  1 , and the invention is not limited to this specific execution. One of ordinary skill in the art will recognize that the benefits of the simplified construction of the present invention can be applied to any actuating device  1  according to the present invention to power a load  40 . 
   More particularly, the actuating device  1  according to the present invention may be powered by a circuit having a transistor  32  in the feedback loop between the microcontroller  20  and the control signal  124 . The microcontroller  20  can be used to count the number of times the control signal  124  is turned on and off during a set period. Furthermore, by charging the capacitor  38 , and depleting it over a known period of time, the microcontroller  20  can be used to provide a discrete time period over which the control signal  124  is activated. 
   Power Supply 
   The exemplary integrated electronic control circuit  10  shown in  FIG. 1  is driven by a power supply  50  which may be an AC or DC power supply  50  having a DC output. Suitable power supplies may include batteries and a standard wall outlet. The power supply  50  supplies a drive power signal  150  to the microcontroller  20  and a control power signal  250  to at least one passive component  30 . The drive power signal  150  can optionally be provided first to an auxiliary power supply unit  90  before being provided to the microcontroller  20 . 
   Drive Circuit 
   The power supply  50  may supply a drive power signal  150  to the microcontroller  20  which may include a drive signal generator  22 . The microcontroller  20  may have an internal drive frequency generator  22  that is used to generate a square wave drive signal  122  with the frequency resolution required to drive the load  40 . The drive signal generator  22  may be programmed with software that will perform the function of frequency generation which uses the number of microcontroller  20  clock cycles between output transitions to generate square waves that are required for driving the load  40 . The frequency of oscillation is a factor that affects power supplied to a load  40 . The load  40  may operate at its resonant drive frequency. Suitable actuators may provide resonant drive frequencies in a range of about 75 KHz to about 175 KHz, alternatively about 80 KHz to about 120 KHz, alternatively about 80 KHz to about 100 KHz, alternatively about 80 KHz. When driven at the resonant frequency, the power consumption of the load  40  increases relative to other frequencies at the same voltage. The resolution may be about 100 Hz to about 1 KHz, alternatively 500 Hz or 1 KHz, alternatively about 750 Hz to about 1 KHz, alternatively 1 KHz depending on the timing of the clock. 
   To determine the resonant frequency, the final control power  238  can be measured by turning off the control signal  124 , and then driving the actuator for thirty cycles and turning the control signal  124  back on and measuring the time it takes to reach the target voltage in the capacitor  38 . The frequency that takes the longest amount of time to charge the capacitor  38  to a predetermined amperage in a frequency sweep is the one that consumes the most power. The drive frequency generator  22  may select the operating frequency that places the highest load on the power supply  50  to be the resonant frequency. The resonant frequency may be is used in further operation to drive the load  40 . 
   When the device  1  is switched on, the resonant frequency is unknown. Thus, before generating liquid droplets of perfume materials, all frequencies in the range may be tested as described above to find the operating frequency of the load  40 . When operating, the resonant frequency may appear to shift, due to variation of circuit parameters with temperature, etc. Therefore, each time the device  1  generates liquid droplets, a single frequency point is measured. When all frequencies in the range have been measured, the operating frequency value is updated, and the process restarts. 
   Control Circuit 
   The power supply  50  may supply a control power signal  250  of about 0.8 to about 15 volts DC, alternatively about 1.5 to about 3 volts DC, at up to about 800 mA, alternatively from about 200 to about 300 mA, to at least one passive component  30  of the integrated electronic control circuit  10 . In one embodiment, the passive component  30  that receives control power signal  250  from the battery is an inductor  34 . The passive component  30  may have a relatively low quiescent power consumption when not under load, and its load current can be estimated by measuring the charge and discharge time of the capacitor  38  as described above. 
   The microcontroller  20  according to the present invention may contain all the functional blocks required to implement not only the drive signal  122  to drive the load  40 , but also the control signal  124  to generate sufficient voltage to power the load  40 . A suitable microcontroller  20  for the integrated electronic control circuit  10  is, for example, a device known by the trade names of Atmel ATTINY13, ATTINY26L, Atmel Megal68, and Sonix SN8P2501B. The microcontroller  20  may have fourteen pins with twelve  10 . 
   In addition to generating a square wave at the resonant frequency to drive the load  40  as mentioned, the microcontroller  20  includes a control signal generator  24  that generates a control signal  124  to at least one passive component  30  for controlling the generation of voltage to supply the final control power  238  to the amplifier  60  to power the load  40 . Passive components  30  may include a transistor  32 , inductor  34 , diode  36 , capacitor  38 , and resistor. The oscillation frequency of the control signal  124  is in a range to properly control the voltage necessary to power the load  40 . In an air freshening system that uses a load  40  in the form of an about 10 nF piezoelectric element, the oscillation frequency of the control signal  124  is between about 200 KHz to about 1 MHz, alternatively, about 400 KHZ to about 750 KHz, alternatively about 450 KHz to about 600 KHz, alternatively about 500 KHz to about 550 KHz, alternatively about 500 KHz. 
   In one embodiment, the control signal  124  is supplied to a transistor  32 . The transistor  32  is an N-Channel Field Effect Transistor or commonly called N Channel FET. The control signal  124  may be provided to the transistor  32  which may allow the inductor  34  to charge and discharge the diode  36  to the capacitor  38 . In this way current is built up within the capacitor  38 . The capacitor  38  may have a capacitance of about 22 uF to about 3300 uF, alternatively about 22 uF to about 2000 uF, alternatively about 47 uF to about 1000 uF, alternatively about 47 uF to about 100 uF, alternatively about 47 uF. 
   The microcontroller  20  may monitor the voltage being charged to the capacitor  38  and determines if the capacitor  28  has achieved its target voltage level by receiving a feedback control signal  138  from the capacitor  38 . Upon reaching the target voltage the control signal  124  is turned off. The passage of the control signal  124  from the microcontroller  20  through the passive components  30  and back to the microcontroller  20  is called a voltage feedback loop. When the voltage level of the capacitor  38  drops below that of the target voltage, due to the fact that it supplies final control power  238  to the amplifier  60 , the control signal  124  may once again turned back on. The final control power  238  may be about 3 to about 10 volts, alternatively about 4 to about 9 volts, alternatively about 5 to about 8, alternatively about 6 to about 7 volts; and about 1 to 1000 mA, alternatively about 100 mA to about 900 mA, alternatively about 100 to about 800 mA, alternatively about 200 mA to about 700 mA, about 200 mA to about 400 mA, alternatively about 200 mA to about 300 mA. 
   The control circuit discussed herein can be practiced within the operation time of the drive circuit discussed above. Specifically, there is downtime during the generation of the drive signal  122 , where the microcontroller  20  is counting clock cycles. This downtime can be used to monitor the output voltage using the above described feedback loop which is already in the circuit of the microcontroller  20  to determine if the voltage level is above or below a predetermined point. Depending on the voltage determination, the microcontroller  20  could then turn on or off the control signal  124 . In addition, the ability to keep track of off-time adds to the ability to control the duty cycle of the control signal  124 , within the same microcontroller  20 , and may increase battery life, thereby increasing the length of time over which the required power is withdrawn. The off time of the control signal  124  may increased to help prolong battery life and this may be done through the duty cycle of the control signal  124 . The lowest duty cycle that will allow the control signal  124  to turn on and off may be generally preferred. When the current duty cycle will not longer allow the control signal  124  to turn off, the duty cycle is increased. Off time is the time where the microcontroller  20  is not generating the wave function of the control signal  124  and is only generating the wave function of the drive signal  122 . 
   Amplifier and Load 
   The air freshening system may have a power amplifier  60  and a load  40  in the form of an actuator. A power amplifier  60  amplifies the power  238  supplied by the passive component  30  and upon receiving the drive signal  122  from the microprocessor  20 , the amplifier  60  sends the final power  260  to the actuator. Suitable actuators may include electromechanical transducers such as piezoelectric elements or piezoelectric crystals and solenoids. In an air freshening system, the actuator may be a round piezoelectric crystal having an optional orifice therethrough. The piezoelectric crystal may be mounted on a substrate having a perforate membrane from which liquid droplets of perfume materials are emitted. The piezoelectric crystals may also be physically de-coupled from the perforate membrane. In both configurations, the piezoelectric crystal may be in fluid communication with the liquid and operatively associated with the perforate membrane such that liquid droplets of perfume material passes through the perforate membrane for diffusion into the atmosphere. The diameter of the perforations may be less than about 30 microns, alternatively less than about 15 microns, alternatively, between about 2 to about 10 microns, alternatively between about 4 to about 8 microns, alternatively, between about 5 to about 7 microns. 
   In this embodiment, the circuit of the amplifier  60  may be configured as a bridge circuit, which may be a resonant bridge circuit. The actuator forms part of the bridge circuit. The drive signal generator  22  may generate a drive signal  122  which may be comprised of two signals 180 degrees out of phase at a desired frequency. The two signals may comprise non-overlapping signals. Operating from about 3 to about 6 volts, alternatively about 5 volts, the microcontroller  20  can generate a drive signal  122  to the amplifier  60  which amplifies the voltage to supply a final power  260  to the actuator in the order of about 32 to about 55 volts peak-to-peak, alternatively about 42 to about 55 volts peak to peak. The final power  260  supplied to the actuator is in the range of about 0.7 watts to about 1.7 watts. 
   Modes 
   The device  1  may have two operating modes, a maintenance mode and a boost mode. The maintenance mode is the default mode which occurs when the device  1  is turned on. The boost mode may be a user activated mode as desired to increase operation of the actuator. In an air-freshener of this type that sprays fluid in two different modes, the integrated electronic control circuit  10  includes a maintenance switch  70  and a boost switch  80 . The maintenance switch  70  may be connected to the microcontroller  20  to control a timer  72  provided by the microcontroller  20  to set the interval at which the drive signal is provided to the power amplifier  60  to control the interval at which the droplet generator is automatically operated. 
   The microcontroller  20  may also provide a boost timer  82  to generate the drive signal  122 , on demand, as a pulse over a predetermined period longer than the pulse at which the load  40  is automatically operated. The boost timer  82  can be operated by a mono-stable boost switch  80  connected to the microcontroller  20 . 
   A maintenance mode is provided wherein a preset quantity of fluid is emitted by the actuator at intervals determined by a user. This is achieved by automatically actuating the actuator for a predetermined length of time, a maintenance switch  70  allowing the user to control how often the actuator emits fluid. The maintenance switch  70  may be a multi-position slide switch that the user may adjust to set the time interval between sprays. 
   The maintenance timer  72  may be used to set the time interval between the maintenance sprays as mentioned above. It also sets the time duration of each spray. The maintenance timer  72  can be provided by software or hardware on the microcontroller  20 . The maintenance switch  70  may be connected to the maintenance timer  72  to allow the user to set the interval between each background spray. 
   In one embodiment of the present invention, the maintenance mode includes a spray period in which the actuator is generating liquid droplets of perfume from the air freshening system and a rest period in which the actuator is not emitting liquid droplets of perfume from the air freshening system. The spray period may be between about 5 milliseconds and about 5 seconds, alternatively between about 10 milliseconds and 1 second, alternatively between about 20 milliseconds and 500 milliseconds, alternatively between about 50 milliseconds and 100 milliseconds. The rest period may be between about 1 second and about 30 hours, alternatively between about 1 second and about 24 hours, alternatively, between about 5 seconds and 12 hours, alternatively between about 5 seconds and about 8 hours, alternatively between about 5 seconds and about 6 hours, alternatively between about 5 seconds and about 4 hours, alternatively between about 5 seconds and about 3 hours, alternatively between about 5 seconds and about 2 hours, alternatively between about 5 seconds and about 1 hour, alternatively between about 5 seconds and about 45 minutes, alternatively between about 5 seconds and 30 minutes, alternatively between about 5 seconds and about 20 minutes, alternatively between about 5 seconds and about 15 minutes, alternatively between about 5 seconds and about 10 minutes, alternatively between about 5 seconds and about 5 minutes, alternatively between about 5 seconds and about 150 seconds, alternatively between about 20 seconds and about 120 seconds, alternatively between about 25 seconds and about 80 seconds, alternatively between about 10 seconds and about 40 seconds. It is understood, however, that periods of time longer than the above ranges of time may be utilized with the present invention. 
   A boost mode can also be provided. In this mode, when the user operates boost switch  80 , the actuator sprays a preset quantity of fluid. A boost timer  82  can be provided as hardware or software in the microcontroller  20 . When the boost switch  14  is pressed, the software executes the boost spray. Activating the boost mode may split the time period additional fluid is to be sprayed into a number of quanta of fixed duration, with a fixed time interval between each quanta. Each quantum may be 1 second, which may be repeated 10 times with a 40 ms time gap between each 60 ms pulse. The 40 ms gap may lower the average flow rate and gives the actuator time to recover between each spray. 
   Typically, the boost mode may emit about 1 mg to about 3 mg of perfume per 3 seconds whereas the maintenance mode emits about 40 mg of perfume per hour during cycle that includes a spray for about 60 milliseconds about every 1 to 60 seconds, alternatively about 5 to about 60 seconds. The microcontroller is programmed to control the 500 KHz signal such that sufficient energy is stored in the capacitor  38  for carrying out a boost cycle for at pre-programmed time or until the perfume is depleted from the device. In one embodiment, the boost mode is at least about 1 second, alternatively at least about 3 seconds, alternatively between about 1 second and about 10 seconds, alternatively between about 3 seconds and about 5 seconds, alternatively about 3 seconds. 
   A problem addressed by use of the boost function may be the deleterious influence on device performance of a static layer of fluid which, in some circumstance may develop over time on the top surface of the load  40 . On some devices it appears that the load  40  has difficulty producing droplets through this film of fluid. It was noticed that the initiation of spraying can move the fluid film away from the spraying area. Thus it was determined that a load  40  suffering from this problem could be cleared by subjecting it to successive initiation operations. 
   The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”. 
   All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern. 
   While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.