Patent Publication Number: US-7723899-B2

Title: Active material and light emitting device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. application Ser. No. 11/265,738, filed Nov. 2, 2005, entitled “Active Material and Light Emitting Device, which is a continuation-in-part of U.S. application Ser. No. 11/050,169, filed Feb. 3, 2005, entitled “Device Providing Coordinated Emission of Light and Volatile Active,” which claims the benefit of U.S. Provisional Application No. 60/541,067, filed Feb. 3, 2004, and also is a continuation-in-part of U.S. application Ser. No. 11/464,419, filed on Aug. 14, 2006, now U.S. Pat. No. 7,538,473, entitled “Drive Circuits And Methods For Ultrasonic Piezoelectric Actuators.” 

   REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   SEQUENTIAL LISTING 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the integrated presentation of ambient conditions. More specifically, the present invention relates to the controlled and coordinated emission of light and an active material, into a given area, such as a room, from a single device. 
   2. Description of the Background of the Invention 
   Because of their wide array of shapes and sizes, as well as the seemingly limitless number of available scents, few things are quite as versatile at setting the ambience in an area as scented candles. Scented candles are not without drawbacks, however. For example, dripping wax can damage furniture and the skin and, in the extreme, an open flame can lead to a structure fire. 
   To account for the common problems associated with candles, electronic lighting devices that have a flickering candle appearance, such as those disclosed in U.S. Pat. Nos. 5,013,972 and 6,066,924, are generally known in the art. In the &#39;972 patent, two side-by-side lamps are alternatingly turned on and off at such frequencies that a flickering is perceived. Similarly, the &#39;924 patent discloses circuitry used to control two light bulbs in close proximity to each other such that the bulbs flicker. Moreover, the circuitry and bulbs of the &#39;924 patent are contained within a container of a size and shape similar to common flat candles. While these patents may suggest devices that mimic the visual aesthetics of a candle, they fail to provide the scented candle experience, i.e., they fail to emit fragrance in addition to light. 
   Fragrance dispensers are also generally known. For example, it is known to emit fragrance from an aerosol container upon the activation of a trigger by a user. Also, other methods utilize the evaporative properties of liquids, or other vaporizable materials, to cause vapors with desired properties to be distributed into the ambient air. For example, U.S. Pat. No. 4,413,779 discloses a glass container containing a fluid into which two rigid porous nylon wicks extend. The wicks contact a rigid plastic porous element. In use, the wicks transport the fluid from the glass container to the ambient air. As a further example of air fresheners, the art is also generally aware of atomizer assemblies for releasing fragrance from a wick that draws fragrant liquid from a reservoir. For example, commonly assigned U.S. Pat. No. 6,296,196 and commonly assigned and copending U.S. patent application Ser. No. 10/412,911, filed Apr. 14, 2003, both discussed in detail below, disclose such assemblies. These references are hereby incorporated by reference. Although these representative devices provide fragrance emission, they do not provide the visual aesthetic of a candle. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the present invention, a light and active material emitting circuit includes an LED and a microprocessor that develops a pulse-width modulated (PWM) waveform. A first feedback circuit is coupled to the LED and an integrator has a first input that receives the PWM waveform, a second input coupled to the first feedback circuit, and an output. An oscillator is coupled to the integrator and includes a logic gate, a first impedance coupled across the logic gate providing positive feedback and a second impedance coupled across the logic gate providing negative feedback. A drive circuit is coupled to the oscillator and a first inductor is coupled between the driver and the LED wherein the LED is caused to flicker. The circuit further includes a piezoelectric actuator and a second inductor coupled to the piezoelectric actuator wherein the piezoelectric actuator and the second inductor form a resonant circuit. A plurality of transistors is coupled to the resonant circuit and a second feedback circuit is coupled to the plurality of transistors. A control circuit is coupled to the second feedback circuit and has an amplifier and an inverter, wherein the control circuit is further coupled to the transistors wherein the control circuit develops the drive waveforms such that the piezoelectric actuator is periodically driven at a resonant frequency. 
   According to a further aspect of the present invention, a circuit for developing drive waveforms for switches coupled to a resonant circuit comprises a feedback circuit coupled to the resonant circuit and a control circuit coupled to the feedback circuit and having first and second interconnected NAND gates. The control circuit is coupled to the switches and develops the drive waveforms wherein the resonant circuit is driven at a resonant frequency. 
   According to another aspect of the present invention, a circuit for developing a drive waveform for an LED includes a microprocessor that develops a pulse-width modulated (PWM) waveform and a feedback circuit coupled to the LED. An integrator has a first input that receives the PWM waveform, a second input coupled to the feedback circuit, and an output. An oscillator is coupled to the integrator including a logic gate, a first impedance coupled across the logic gate providing positive feedback and a second impedance coupled across the logic gate providing negative feedback. A drive circuit is coupled to the oscillator and an inductor is coupled between the drive circuit and the LED wherein the LED is caused to flicker. 
   Other aspects and advantages of the present invention will become apparent upon consideration of the following detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a light and active material emitting device according to a first embodiment; 
       FIG. 2  is an exploded perspective of the device of  FIG. 1 ; 
       FIG. 3  is a side view of the device of  FIG. 1 , with the base removed; 
       FIG. 4  is a perspective view of components of the device of  FIG. 1 ; 
       FIG. 5  is a perspective view of the device of  FIG. 1  disposed in a holder; 
       FIG. 6  is a side view of a light and active material emitting device according to a second embodiment; 
       FIG. 7  is an exploded perspective view showing the relationship of the device of  FIG. 6  with a base; 
       FIGS. 8A-8C  are views of a light and active material emitting device according to a third embodiment; 
       FIG. 9  is a perspective view of a light and active material device according to another embodiment; 
       FIG. 10  is a perspective view of a light and active material emitting device according to still another embodiment; 
       FIG. 11  illustrates further embodiments of a light and active material emitting device; 
       FIGS. 12A-12D  illustrate configurations of holders to be used according to various other embodiments of 
       FIG. 13  is a cross-sectional view illustrating an active material dispenser; 
       FIG. 14  is a cross-sectional view illustrating the active material dispenser shown in  FIG. 13 ; 
       FIG. 15A  is a top isometric view of a further embodiment of a light and active material emitting device; 
       FIG. 15B  is a top isometric view of the device of  FIG. 15A ; 
       FIG. 16  is a top isometric view illustrating the device of  FIG. 15A  with a cover portion removed therefrom; 
       FIG. 17  is an exploded view of the device of  FIG. 15A  with a cover portion and a housing cover removed therefrom; 
       FIG. 18  is a is a top isometric view illustrating a housing cover as depicted in the device of  FIG. 15A ; 
       FIG. 19  is a cross-sectional view taken generally along the lines  19 - 19  of  FIG. 15A ; 
       FIG. 20  is a top isometric view illustrating electronics of the device of  FIG. 15A ; 
       FIG. 21  is a is a bottom plan view illustrating the device of  FIG. 15A ; 
       FIG. 22  is a cross-sectional view taken generally along the lines  22 - 22  illustrating a cover portion of the device of  FIG. 15A ; 
       FIG. 23  is an isometric view illustrating the device of  FIG. 15A  disposed within a container; 
       FIG. 24  is a cross-sectional view taken generally along the lines  24 - 24  of  FIG. 23 ; 
       FIG. 25  is a cross-sectional view of one embodiment of a light control device; 
       FIGS. 26-28  are cross-sectional views of three variations of another embodiment of a light control device; 
       FIG. 29  is a cross-sectional view of yet another embodiment of a light control device; 
       FIG. 30  is a cross-sectional view of still another embodiment of a light control device; 
       FIG. 31  is a cross-sectional view of another embodiment of a light control device; 
       FIG. 32  is a block diagram of an integrated circuit that implements a control device according to yet another embodiment together with external circuitry connected thereto; 
       FIG. 33  is a schematic diagram functionally illustrating the random number generator implemented by the integrated circuit of  FIG. 32 ; 
       FIG. 34  is a series of waveform diagrams illustrating a portion of the operation of the integrated circuit of  FIG. 32 ; 
       FIGS. 35A and 35B , when joined along the similarly lettered lines, together illustrate programming executed by the logic of  FIG. 32  to control one or two LED&#39;s; 
       FIG. 36  is a diagrammatic view of the switch S 2  of  FIG. 32 ; 
       FIG. 37  is a schematic diagram functionally illustrating operation of the ramp oscillator of  FIG. 32 ; 
       FIG. 38  is a waveform diagram illustrating the voltage developed at the terminal CSLOW of  FIG. 32 ; 
       FIG. 39  is a waveform diagram illustrating the voltage developed at the terminal GDRV of  FIG. 32 ; 
       FIG. 40  is a state diagram illustrating operation of the integrated circuit of  FIG. 32  to control an active material dispenser; 
       FIG. 41  is a schematic diagram of a further circuit according to the present invention for controlling an LED and an active material emission device; and 
       FIGS. 42 and 43  are flowcharts illustrating programming executed by the microprocessor of  FIG. 41  to implement alternative embodiments of the present invention. 
   

   Throughout the FIGS., like or corresponding reference numerals have been used for like or corresponding parts. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention provides a device that emits both light and an active material. Preferably, the present invention provides a single device that mimics both the visual and olfactory aesthetic of a scented candle, without an open flame and with an improved fragrance delivery system. 
   While a preferred embodiment of the present invention includes emission of an active material, preferably a fragrance, and much of the discussion below will be with regard to emission of a fragrance, we also contemplate that the dispenser may alternatively dispense other substances, such as a disinfectant, a sanitizer, an insecticide, an insect repellant an, insect attractant, air purifiers, aromatherapy, scents, antiseptics, odor eliminators, air-fresheners, deodorizers, and other active ingredients that are usefully dispersed into the air. As will be recognized by one of ordinary skill in the art, other active ingredients can be introduced to the ambient environment via dispensers in much the same way as fragrances. 
   As generally seen in the FIGS., preferred embodiments of the present invention include a device for emitting light and an active material. The device preferably includes an electrically-powered light source, an active material dispenser, a power source, control circuitry, and a support structure. All of these components work together to provide a fragrant aroma and the appearance of a flickering flame, the flickering effect being provided by the electrically-powered light source. 
   Light Source 
   The light source is an electrically-powered light emitting device. The light source comprises one or more light emitting diodes (LED&#39;s). Particularly, in  FIGS. 1-7  a single LED  106  or  206  is used, while in  FIGS. 8A-8C , the light source includes LED&#39;s  306   a ,  306   b . Other conventional lighting devices (including, for example, incandescent, halogen, fluorescent, etc.) may alternatively be used as the light source. 
   As is generally understood, LED&#39;s offer various features not found in other conventional lighting devices. In particular, as is well known in the art, by manipulating the duty cycle of an LED, light emitted from the LED can be controlled. For example, light can be emitted at perceptible intermittencies, or it can be emitted such that it is perceived to be continually emitted. Moreover, increasing the duty cycle of an LED will increase the intensity of light emitted and/or the perceived color. 
   In the embodiments in which a single LED is used, the LED is controlled to have a varying intensity, thereby providing a flickering effect. When two LED&#39;s are used, as in  FIGS. 8A-8C , the two LED&#39;s  306   a ,  306   b  are preferably arranged one above the other, i.e., the LED 306   a  is on a side of the LED  306   b  opposite to a base of the light and fragrance emitting device  300 . Preferably, the upper LED  306   a  is controlled to emit light at a perceivable intermittence, while the lower LED  306   b  is controlled such that light is perceived to be emitted continuously. In this fashion, the LED&#39;s  306   a ,  306   b  work to create a flicker effect. When, for example, a conventional candle is lit, the base of the flame is steady, while the portion of the flame further from the wick appears to flicker. The present arrangement of the LED&#39;s  306   a ,  306   b  mimics this visual characteristic. It is preferred that LED&#39;s having a yellowish or amber hue be used. Specifically, it is preferred that the LED&#39;s used have a wavelength of emission in the range of from approximately 580 nanometers to approximately 600 nanometers, and it is even more preferred that the LED&#39;s used have a wavelength of emission in the range of from approximately 585 nanometers to approximately 595 nanometers. Optionally, the LED&#39;s  306   a ,  306   b  may be positioned side-by-side instead of one above the other. Still optionally, one or both of the LED&#39;s  306   a ,  306   b  may be white and a color or image filter may be disposed over the LED to project an image or a color therefrom. 
   Of course, we anticipate modifications to the light source of our preferred embodiment. For example, more than two LED&#39;s can be used, perhaps, to create the perception of a larger flame. Also, LED&#39;s of many colors are known and could be used, for example to more closely resemble a flame by using hues that are reddish, orangish, and/or yellowish. The colors can also be made to change, for example, using RGB LED&#39;s. By so varying the types of LED&#39;s used, as well as their arrangement, numerous aesthetics can be obtained, including varied colored shows, colored flames, and colored flickers. And, by adjusting the duty cycles of the LED&#39;s, the brightness of the light may also be reduced or intensified, as dictated by design preference. 
   Moreover, when multiple LED&#39;s are used, it is not required that one LED provide a perceptibly constant light emission while the other LED  306   a  provides a flicker effect. One or both may be held perceptibly constant and one or both may emit flickering light. (It would be recognized by one of ordinary skill in the art that when using pulse-width modulation to control one or more LED&#39;s perceptibly constant and flicking lights are likely both being flickered at a high frequency imperceptible to an observer. Flickering and constant light should be understood herein to refer to perceived effects.) 
   Active Material Dispenser 
   An active material dispenser is preferably provided integrally with the present invention. The active material dispenser preferably holds a replaceable container, or reservoir, having an active material in any one of a number of conventional forms, including gel and liquid forms. The active material may be vaporized by the application of heat and emanated from the device. In such a case, the dispenser may have a controllable heating device to vary the rate at which vapor is driven from the fragrance or a mechanical controller for controlling the airflow around the fragrance to be vaporized (such as a shield or fan). 
   While active material dispensers are generally well known, a preferred active material dispenser is a wick-based emanation system. More preferably, the active material dispenser uses an atomizer to emanate the active material from the wick. Such an arrangement is shown in  FIGS. 13 and 14 . 
   Specifically, the evaporative active material dispenser  4  comprises an atomizer assembly including an orifice plate  462 , and a replaceable reservoir  326 . The reservoir  326  is replaceable and contains an active material in the form of a fluid. A wick  464  is disposed in the reservoir  326 . The wick  464  operates by capillary action to transfer liquid from within the reservoir  326 . The reservoir  326  is preferably removable by a user and may be replaced with another reservoir  326  (for example, when the fluid is exhausted or when a different type of fluid is desired). When replaced in this manner, the wick  464  transfers fluid from the reservoir  326 . 
   In addition to including the orifice plate  462 , the atomizer assembly further comprises at least one resilient, elongated wire-like support  466  shaped to resiliently support the lower surface of the orifice plate  462  and a spring housing  468 . A spring  470 , contained within the spring housing  468 , resiliently presses on the upper surface of the orifice plate  462 . Rather than pressing on the orifice plate  462  directly, the spring  470  may alternatively, or additionally, press on a member, such as an actuator element  472  (made of, for example, piezoelectric ceramic material, which is connected to the orifice plate  462 . Together, the wire-like support  466  and the spring  470  hold the orifice plate  462  in place in a manner that allows the orifice plate  462  to move up and down against the resilient bias of the wire-like support  466 . 
   The actuator element  472  is preferably annularly shaped and the orifice plate  462  is preferably circular. The orifice plate  462  extends across and is soldered or otherwise affixed to the actuator element  472 . Constructions of vibrator-type atomizer assemblies are described, for example, in Helf et al. U.S. Pat. No. 6,293,474, Denen et al. U.S. Pat. No. 6,296,196, Martin et al. U.S. Pat. No. 6,341,732, Tomkins et al. U.S. Pat. No. 6,382,522, Martens, III et al. U.S. Pat. No. 6,450,419, Helf et al. U.S. Pat. No. 6,706,988, and Boticki et al. U.S. Pat. No. 6,843,430, all of which are assigned to the assignee of the present application and which are hereby incorporated by reference herein. Accordingly, the atomizer assembly will not be described in detail except to say that when alternating voltages are applied to the opposite upper and lower sides of the actuator element  472 , these voltages produce electrical fields across the actuator element  472  and cause it to expand and contract in radial directions. This expansion and contraction is communicated to the orifice plate  462  causing it to flex such that a center region thereof vibrates up and down. The center region of the orifice plate  462  is domed slightly upwardly to provide stiffness and to enhance atomization. The center region is also formed with a plurality of minute tapered orifices that extend through the orifice plate  462  from the lower or under surface of the orifice plate  462  to its 
   In operation, electrical power, in the form of high frequency alternating voltages, is applied to the opposite upper and lower sides of the actuator element  472 , as described above. A suitable circuit for producing these voltages is shown and described in U.S. Pat. No. 6,296,196, noted above. As described in that patent, the device may be operated during successive on and off times. The relative durations of these on and off times can be adjusted by an external switch actuator (not shown) on the outside of the housing and coupled to a switch element on the microprocessor. In other embodiments, the on and off times may be controlled by a preset program, or controlled by a user interface working through a processor, such as a user control. 
   When the atomizer assembly is supported by the wire-like support  466 , the orifice plate  462  is positioned in contact with the upper end of the wick  464 . The atomizer assembly is thereby supported above the liquid reservoir  326  such that the upper end of the wick  464  touches the underside of the orifice plate  462 . Thus, the wick  464  delivers liquid from within the liquid reservoir  326  by capillary action to the top of the wick  464  and then by surface tension contact to the underside of the orifice plate  462 , which, upon vibration, causes the liquid to pass through its orifices and be ejected from its opposite side (i.e., the upper surface) in the form of small droplets. 
   In one embodiment, a horizontal platform serves as a common structural support for both the reservoir  326  and the atomizer assembly. In this manner, the reservoir  326 , and, in particular, the upper end of the wick  464  disposed therein, are aligned with the orifice plate  462 . Moreover, because the atomizer assembly and the orifice plate  462  are resiliently mounted, the upper end of the wick  464  will always press against the under surface of the orifice plate  462  and/or the actuator element  472  irrespective of dimensional variations which may occur due to manufacturing tolerances when one reservoir  326  is replaced by another. This is because if the wick  464  contained in the replacement reservoir  326  is higher or lower than the wick  464  of the original liquid reservoir  326 , the action of the spring  470  will allow the orifice plate  462  to move up and down according to the location of the wick  464  in the replacement reservoir  326 , so that the wick  464  will press against the underside of the orifice plate  462  and/or the actuator element  472 . It will be appreciated that the wick  464  preferably is formed of a substantially solid, dimensionally stable material so that it will not become overly deformed when pressed against the underside of the resiliently supported orifice plate  462 . The features of the horizontal platform on which the atomizer is disposed will be discussed further below. 
   As shown in  FIGS. 13 and 14 , the wick  464  extends from inside the liquid reservoir  326  up through a plug  474  in the top of the reservoir  326  to contact the orifice plate  462  and/or the actuator element  472 . (The plug  474  holds the wick  464  within the liquid reservoir  326 .) The wick  464  has longitudinally extending capillary passageways that draw liquid up from within the reservoir  326  to the upper end of the wick  464 . In lieu of the capillary wick  464 , we envision that a capillary member (not shown) may alternatively be used. Such a member generally includes plural capillary passageways on an exterior surface thereof. These passageways act, via capillary action, to transfer fragrance from the liquid reservoir  326  to the orifice plate  462  and/or the actuator element  472 . 
   A more detailed explanation of the atomization device described above may be found in commonly assigned Martens et al. U.S. Publication No. 2004/0200907. In addition, a more detailed explanation of the support structure for the atomizing device may be found in commonly assigned Helf et al. U.S. Pat. No. 6,896,193. The disclosure of the &#39;907 publication and the &#39;913 patent are hereby incorporated by reference. 
   Of course, other active material emitting devices may be used in addition to the atomizer assembly. Specifically, we envision that evaporation devices, heat-assisted evaporation devices, and fan-assisted evaporation devices, among others, could be used in addition to the piezoelectrically actuated atomization device described above. Moreover, even within each type of dispenser, variations are possible, as would be appreciated by one of ordinary skill in the art. 
   Power Source 
   The power source supplies power to light the light source, and if required, to operate the active material dispenser (for example, to supply voltages to the upper and lower surfaces of the actuator plate in the atomization-type active material dispenser discussed above). Also, the power source may be used to power additional components (although not shown, these additional components may include, e.g., a fan). In a preferred embodiment, the power source comprises one or more batteries. When one battery is used, a voltage step-up may be used to ensure sufficient power. The batteries may be replaceable, or they may be rechargeable. If rechargeable batteries are used, they may be removed for recharging, or an adapter may be provided on the device such that the batteries can be charged without being removed from the device. For instance, a receptacle (not shown) may be incorporated into the device to receive a plug that supplies power from, for example, an electrical outlet. It is not required, however, that the power source comprises batteries. For example, power for the device may be derived directly from an electrical outlet. As will be appreciated by one of ordinary skill, however, the use of alternate power sources may require that the device further include an AC to DC converter. 
   Control Circuitry 
   As used throughout, the term “control circuitry” is intended to be a representative term that encompasses all controls that can be used to embody the light and active material emitting device. For example, the preferred embodiments are discussed below with reference to microprocessors and/or circuit boards, and microprocessors and circuit boards constitute control circuitry. Further contemplated examples of control circuitry that may be used are an Application Specific Integrated Circuit (ASIC), a microprocessor, and an arrangement of one or more resistors and/or capacitors. Control circuitry may or may not include software. These examples of control circuitry are not limiting, however. Other control circuitry may also be used. 
   The control circuitry is generally used to control the operation of the device and is powered by the batteries. Specifically, the control circuitry is designed to provide the signals for controlling the operation of the light source. When one or more LED&#39;s are provided as the light source, the microprocessor may alter the duty cycles of the LED&#39;s to control the perceived intensity of the emitted light, thereby creating the candle-like flicker effect. Alternatively, instead of altering the duty cycles, the microprocessor may otherwise adjust the light emission properties of the LED&#39;s. For example, methods utilizing an analog sine wave or a digital potentiometer are generally known in the art. In other embodiments, when at least two LED&#39;s are used, as in  FIGS. 8A-8C , and one LED  306   b  receives a constant current to emit light constantly, that LED  306   b  can be controlled separately from a circuit board, either to receive a power supply from the power source, when the device is turned on, or to not receive power, when the device is turned off. In other words, when one LED  306   b  constantly emits light, it is not necessary to provide means for adjusting the duty cycle thereof (such as the microprocessor). In this case, the microprocessor may adjust the operation of only the LED&#39;s that flicker. In other embodiments the constant emission LED may be controlled by pulse-width modulation set by the microprocessor such that the frequency of the pulse-width is imperceptible to an observer. In this manner, the intensity of the constant emission LED may be varied slightly to add to the overall flicker presentation. 
   The microprocessor may include circuits for converting power from the batteries to the high-frequency alternating voltages required to expand and to contract the actuator member  472 , thereby emitting active material from the active material dispenser  4 . In addition, the microprocessor may control a fan and/or a heating element, if such are used. Furthermore, the microprocessor may include controls for automatically turning on and or off one or both of the light source and the active material dispenser. 
   Support Structure 
   A support structure is provided to support the light source, the active material emitter or atomizer assembly, the power source, and the microprocessor, or some combination thereof. The term “support structure” is intended to encompass any and all of a chassis, a housing, a holder, and a base, as those terms are used in the description below, as well as similar structures used to support or contain the features of device. 
   Embodiments of the Light and Active Material Emitting Device 
   Having now generally described the components of the present invention, discussion will now be made of various embodiments of a light and active material emitting device. These embodiments include various novel arrangements of the above-described components, as well as additional features. 
   The first embodiment is depicted in  FIGS. 1-5  and. As seen best in  FIGS. 2 and 3  a chassis  102  is provided that comprises a chassis cover  102   a , a chassis upper portion  102   b , and a chassis lower portion  102   c . Disposed on the chassis  102  are two batteries  118 , a wick-based atomizer assembly  108 , a single LED  106 , and two printed circuit boards  114 ,  116 . Each of two microprocessors  110 ,  112  are disposed on the circuit boards  114 ,  116 . As shown, the chassis cover  102   a  and the chassis upper portion  102   b  are joinable to form a cavity therebetween, and the chassis lower portion  102   c  depends downwardly from a bottom of the chassis upper portion  102   b . In this embodiment, the atomizer assembly  108 , the LED  106 , the microprocessors  110 , 112 , and the printed circuit boards  114 ,  116  are disposed within the cavity formed between the chassis cover  102   a  and the chassis upper portion  102   b . Electrical contacts  122 , which the batteries  118  contact to supply the device  100  with power are disposed on the lower portion  102   c  of the chassis  102 , with batteries  118  disposed in contact with the electrical contacts  122 . 
   In the embodiment of  FIGS. 1-5 , the batteries  118  are removably securable to the lower portion  102   c  of the chassis  102 . A battery retainer  120  may also be provided to aid in maintaining attachment of the batteries  118  to the chassis  102 . When the batteries  118  are to be detached from the chassis  102 , the retainer  120  must first be removed. Also in this embodiment, an entryway (not shown) is formed in the bottom of the upper portion  102   b  of the chassis  102 , proximate to the atomizer assembly  108 , so that a reservoir  126  containing a liquid to be atomized may be easily removed from, and reattached to, the atomizer assembly  108 . Accordingly, this arrangement provides a user with access to the batteries  118  and to the reservoir  126  (for example, to enable changing the batteries  118  and the reservoir  126 ), but the remaining components are maintained within the cavity formed between the chassis cover  102   a  and the chassis upper portion  102   b , reducing the possibility of contact with, and possible damage to, those components. 
   As shown in  FIGS. 1 and 3 , in the first embodiment, a protrusion, or tip  124  extends axially upwardly the top of the chassis cover  102   a . Preferably, the LED  106  is disposed within the tip  124 , such that light emitted from the LED  106  is diffused by, and transmitted through, the tip  124 . As depicted in  FIG. 2 , the tip  124  is a separate component of the device  100 , disposed within an aperture formed through the top of the chassis  102 . The tip  124  may also be formed integrally with the chassis  102 . By making the tip  124  a separate piece, however, the tip  124  may be replaceable, e.g., with other, differently constructed, or colored, tips. In the case of a colored tip, the LED  106  may be a white LED in order to transmit light in the color of the colored tip. Also, a separate tip  124  may be formed of a material other than that used for the chassis. For example, the tip  124  may be formed of a material through which light is transmitted, e.g., plastic, glass, wax, and the like. Additionally the tip  124  may be formed of a material such that the tip  124  continues to glow, even after the LED  106  is shut off. 
   Apertures other than that formed for insertion of the tip  124  may also be formed in the chassis  102   a . For example, an emissive aperture  136  is preferably formed through a top surface of the chassis  102 , above the atomizer assembly  108 , such that the active material emitted by the atomizer passes through the emissive aperture  136 , into the ambient environment. Furthermore, apertures may be formed in the chassis  102 , through which switches are disposed. For example, an emitter controlling switch cover  128  (that cooperates with a slidable switch (not-shown)), in communication with the microprocessor  112  that controls the timing of the duty cycle applied to the atomizer assembly  108 , may be provided to enable a user to manually adjust an amount of active material emitted. In this manner, the user can optimize the emission amount, based on outside considerations, such as room size, and the like. Furthermore, an on/off switch or button  130  may also be provided in an aperture formed through the chassis  102 , to turn one or both of the LED  106  and the atomizer  108  on and off For example, as shown in  FIG. 1 , an on/off toggle switch  132  that is electrically connected to the LED  108 , is disposed in an aperture through the top surface of the chassis  102 , thereby enabling a user to turn the LED  108  on and off. Although not shown, a similar toggle switch, a push button, or the like, may also be provided for turning the atomizer assembly  108  on and off. In other embodiments, the chassis  102  may have exposed section, such that apertures need not be formed. 
   The chassis  102 , with attached components, is preferably detachably engageable with a base, or cup  134 . The engagement of the chassis  102  with the base  134  forms a unitary housing in which the atomizer assembly  108 , reservoir  126 , batteries  118 , and controls are disposed. The base  134  is generally cylindrical, including a sidewall and a bottom surface and the top of the base is open. The upper portion  102   b  of the chassis  102  is also generally cylindrical, with an outer diameter substantially the same as that of the base  134 . By lowering the chassis  102  into the base  134 , the lower portion  102   c  of the chassis  102  becomes disposed within the base  134 , and the upper portion  102   b  of the chassis  102  is disposed proximate to the open top of the base  134 . The unitary housing thus formed has the appearance of a cylinder, with a tip protruding axially upwardly from approximately a central portion of the top of the cylinder. 
   While one of ordinary skill in the art would understand that there are many ways for removably engaging the chassis with respect to the base, a preferred method of engagement for this embodiment is described as follows. A substantially C-shaped receptacle is formed on the lower portion of the chassis  102  and a protrusion extends axially upwardly from the bottom surface of the base  134 . When the chassis  102  is lowered into the base  134 , the C-shaped receptacle of the lower portion  102   c  of the chassis  102  receives therein the protrusion formed in the base  134 . In this way, proper alignment of the chassis  102  within the base  134  is achieved. Moreover, as should be understood, because the chassis  102  and the base  134  each has a cylindrical footprint and the protrusion and C-shaped receptacle are positioned on respective axes, the chassis  102  is easily attached to the base  134  regardless of the rotational orientation of the chassis  102  with respect to the base  134 . 
   Preferably, the dimensions of the chassis  102  and base  134  combination are anywhere from between approximately one inch and approximately six inches in diameter and preferably anywhere from between approximately one inch and approximately six inches in height. Of course, the dimensions may be larger or smaller, depending on the desired aesthetic. Also, because as described above at least a portion of the flickering LED  106  is disposed within the tip  124 , the tip  124  has the appearance of a conventional candle flame. All or a portion of the rest of the device  100  may also be light transmissive. Light transmissive materials that may be used include glass, plastic, wax, and the like. Furthermore, by moving the LED within the tip, a more realistic perception of a conventional candle may be obtained. 
   Thus, according to the first embodiment, the combination of the chassis  102  and base  134 , as a result of their likeness to a conventional candle, may be provided to a consumer to be used with existing votive holders for conventional candles. Alternatively, the device can be embodied in the combination of chassis  102  and base  134  with holder  104  (as shown in  FIG. 4 ). Furthermore, it should also be understood that the chassis  102  may be designed to stand alone, i.e., without the base. For example, the lower portion  102   c  of the chassis  102  may be designed to enable the entire chassis  102  to stand on its own. 
   A second embodiment will now be described with reference to  FIGS. 6 and 7 . This embodiment includes many of the same components as discussed above with respect to the first embodiment, and descriptions thereof will not be repeated. 
   According to this second embodiment, a chassis  202  (different from the chassis  102  of the first embodiment) is provided. An atomizer assembly  208 , an LED  206 , two circuit boards, a microprocessor, and a battery  218  are disposed on the chassis  202 . As illustrated, the chassis  202  includes a top  202   a , an upper portion  202   b , disposed below the top  202   a , and a lower portion  202   c , disposed below the upper portion  202   b . The atomizer assembly  208  is arranged on the upper portion  202   b  of the chassis  202 , and a reservoir  226  containing a fluid to be atomized by the atomizer assembly  208  is removably matable to the atomizer assembly  208 . The lower portion  202   c  of the chassis  202  is disposed sufficiently below the upper portion  202   b  of the chassis  202  so as to facilitate removal and replacement of the reservoir  226 . The lower portion preferably includes an inner cavity in which the controls, i.e., circuit board(s) and microprocessor(s) (not shown), are disposed. 
   The LED  206  is disposed proximate to a top surface of the lower portion  202   c  of the chassis  202 . More specifically, the LED  206  of this embodiment is disposed on a circuit board disposed within the inner cavity of the lower portion  202   c  of the chassis  202 . An aperture is formed through a top of the lower portion  202   c  of the chassis  202 , and at least a portion of the LED  206  protrudes through the aperture. The battery  218  is disposed below the lower portion of the chassis  202 . As would be appreciated by one of skill in the art, electrical leads and the like may be necessary for communication between the battery  218 , the controls, the LED  206 , and the atomizer assembly  208 . 
   As shown in  FIG. 7 , the chassis  202  is removably placeable within a base  234 . The base  234  is generally cylindrical, with a bottom surface (not shown) and an open top. The chassis  202  is received in the base  234  through the open top. The chassis  202  and the base  234 , when the chassis  202  is placed in the base  234 , form a unitary housing in which the LED  208 , an active material emitter  236 , the controls, and the battery  218  are disposed. Preferably, the chassis  202  and the base  234  are configured such that the top surface of the chassis  202  is disposed within the open top of the base, and the housing formed by the combination of the chassis  202  and the base  234  resembles a conventional pillar candle. 
   Similar to the first embodiment, the housing of the second embodiment also preferably includes an emission aperture aligned with the atomizer assembly  208 . Specifically, because in this embodiment the atomizer is arranged below the top  202   a  of the chassis  202 , the emission aperture  236  is formed through the top  202   a  of the chassis  202 . In this manner, liquid atomized within the housing may be released into the ambient environment. 
   Again, similar to the first embodiment, means are also provided for adjusting the amount of active material emitted by the emitter  208  and for turning the LED  206  on and off. As shown in  FIGS. 6 and 7 , a slidable switch  228 , in communication with the microprocessor that controls the atomizer assembly  208 , is disposed on the lower portion  202   c  of the chassis  202 . The slidable switch  228  is manually adjustable between multiple positions to regulate the frequency at which the atomizer assembly  208  emits the substance contained in the reservoir  226 . In addition, a push button  230  is disposed on the top  202   a  of the chassis  202  for turning the LED  206  on an off. 
   As will be appreciated from the FIGS., because the controls, i.e., the circuit boards and microprocessor, associated with the atomizer assembly  208  and the LED  206  are disposed within the lower portion  202   c  of the chassis  202 , and the atomizer assembly  208  and the push button  230  are disposed proximate to the top  202   a  of the chassis  202 , electrical wires are provided to convey controls from the lower portion  202   c  of the chassis  202  to the atomizer  280 , and a post  252  is provided for transmitting the actuation of the push button  230  disposed on the top  202   a  of the chassis  202  to a switch on the circuit board that turns the LED  206  on and off. In a similar regard, as it may also be beneficial to have the slider switch  228  for adjusting emission of the fluid contained in the reservoir  226  disposed on the top of the housing (for example, for ease of access for the user), it may also be necessary to provide a mechanical, an electrical, and/or an electro-mechanical means for connecting the slider switch and the appropriate controls. 
   According to this second embodiment, a light and substance emitting device  200  is provided. Preferably, as mentioned above, the housing (i.e., the combined chassis  202  and base  234 ) of the device  200  is configured and sized to resemble a conventional pillar candle. As should be understood, since the LED  206  emitting the flickering light is disposed within the housing, much of the light will be transmitted through the sidewall of the base  234 . Accordingly, at least a portion of the base  234  should be light transmissive. In addition, at least a portion of the chassis  202  may also be light transmissive. To these ends, all or a portion of the chassis  202  and/or the base  234  may be formed of one or more of glass, plastic, wax, and the like. 
   Variations of this second embodiment are also contemplated. For example, while the holder  234  is generally cylindrical, such is not required. Rectangular, square, and a myriad of other shapes and sizes are contemplated. In addition, while the chassis  202  is inserted through a top of the base  234 , such is not required. For example, the base may be open at the bottom, such that the base is slid over the chassis  202 , or the base  234  and chassis  202  may be integrally formed, with access panels for replacing the reservoir  226 , battery  218 , and the like. 
   A third embodiment will now be described with reference to  FIGS. 8A-8C ,  9 , and  10 . In this embodiment a light and active material emitting device  300  includes a chassis  302  comprising a chassis cover  302   a  and a chassis base  302   b  which together form a cavity that encases each of two LED&#39;s  306   a ,  306   b , an active material emitter  308 , two batteries  318 , and a printed circuit board with microprocessor  310 . The LED&#39;s  306   a ,  306   b  are connected either directly or indirectly to both of the batteries  318  and the microprocessor  310 . In this embodiment, the LED&#39;s  306   a ,  306   b  are preferably located substantially centrally with respect to a top surface of the device, and above the active material emitter  308 , the batteries  318 , and the microprocessor  310 , i.e., on a side of the active material emitter  308 , the batteries  318 , and the microprocessor  310  opposite to the chassis base  302   b . At least a portion of the LED&#39;s  306   a ,  306   b  are preferably located above a top surface of the chassis cover  302   a . By placing the LED&#39;s  306   a ,  306   b  above the other components in this manner, the emission of light is not impeded by these components, so shadows are substantially prevented, and a more realistic-looking flame is created. 
   The chassis  302  of the embodiments of  FIGS. 8A-8C  preferably includes a horizontal platform  342  (preferably disposed on the chassis base  302   b ) for aligning the active material emitter  308  within the chassis  302 . The platform  342  preferably has a platform aperture  344  therethrough with one or more cutouts  346  formed on a periphery of the platform aperture  344 . Preferably, the replaceable reservoir  326  comprises one or more nubs  348  (one corresponding to each of the cutouts  346  formed in the platform  342 ) formed on the reservoir  326 . To insert a reservoir  326 , a portion of the reservoir  326  is passed through the platform aperture  344  of the platform  342 , with the nubs  348  passing through the cutouts  346 . Once the nubs  348  clear the cutouts  346 , the reservoir  326  is rotated such that the nubs  348  rest on the upper surface of the platform  342 . Also, as discussed above, attached to the top of the platform  342  is the wire like-support  466  (not shown in  FIGS. 8A-8C ) that supports the atomizer assembly  308 . 
   Further, inner surfaces of the chassis  302  may contain various protrusions. These protrusions are preferably provided to aid in properly aligning various components within the chassis  302  and/or to protect components within the chassis  302 . For example, a vertical protrusion  350  (shown in  FIG. 8C ) partitions an area for containing the fragrance emitter  308  from an area having the microprocessor  310 . In this fashion, the microprocessor  310  is not accessible when the reservoir  326  is replaced, and, accordingly, inadvertent damage to, or accidental contamination of, the microprocessor  310  is averted. 
   The chassis cover  302   a  is designed such that it can be placed on the chassis base  302   b , thus forming a unitary device  300 . A protrusion or tip  324  is preferably disposed approximately centrally on the chassis cover  302   a . The tip  324  extends generally axially, in a direction away from the chassis base  302   b  and forms a cavity in which the LED&#39;s  306   a ,  306   b  are disposed when the chassis cover  302   a  is placed on the chassis base  302   b . (As discussed above, the LED&#39;s  306   a ,  306   b  are preferably arranged one on top of the other.) The tip  324  is substantially conical in shape and is preferably made of a material that diffuses the light emitted by the LED&#39;s  306   a ,  306   b . However, it may be desirable to alter the shape of the protrusion, when, for example, more than two LED&#39;s are used, or the housing is relatively wide. For instance, the tip  324  may be more dome-shaped when a wider tip  324  is used with a wide device  300  (so as to keep the tip  324  relatively close to the chassis  302 ). 
   The tip  324  is preferably between approximately one-eighth of one inch and approximately three inches high and between approximately one-eighth of one inch and approximately three inches wide. The remainder of the device  300  is preferably between about two inches and about ten inches high and preferably between about one and one-half inches and about six inches wide. Thus configured, the device  300  can substantially take on the size and shape of various conventional candles, while the tip  324 , by encapsulating the LED&#39;s  306   a ,  306   b , simulates a flame. 
   The chassis cover  302   a  also includes an emission aperture  336  therethrough. When the chassis cover  302   a  is placed on the chassis base  302   b , the emission aperture  336  aligns with the active material emitter  308 . In particular, the emission aperture  336  is formed such that an active material dispensed by the active material emitter  308  passes through the chassis cover  302   a  to the ambient air, i.e., the chassis cover  302   a  does not impede the dissemination of the active material from the active material emitter  308 . 
   The chassis cover  302   a  is preferably secured to the chassis base  302   b , although such is not required. For example, as shown in  FIG. 8A , the chassis cover  302   a  may be removably attached to the chassis base  302   b  such that access to, for example, the reservoir  326  and/or the batteries  318 , may be gained for replacement purposes. When the chassis cover  302   a  is removably attachable to the chassis base  302   b , a locking mechanism may be employed. For example, attractive magnets may be situated on the chassis cover  302   a  and the chassis base  302   b , or the chassis cover  302   a  may include a feature that is designed for compatibility with a mating feature of the chassis base  302   b . In this manner, only specific covers and bases can be used. 
   In another aspect, we contemplate that the chassis base  302   b  and the chassis cover  302   a , when secured together to form the unitary device  300 , may be relatively movable. Specifically, when the chassis cover  302   a  is cylindrical, it may be rotatable on the chassis base  302   b . For example, the rotation of the chassis cover  302   a  may turn on and off the LED&#39;s  306   a ,  306   b  and/or the active material emitter  308 . 
   As an alternative to the removable chassis cover  302   a , when, for example, a new active material is desired or the reservoir  326  is empty, the device  300  may include a hatchway for purposes of replacing the reservoir  326 . Examples of two contemplated hatchways  338   a ,  338   b  are illustrated in  FIGS. 9 and 10 , respectively. 
   As shown in  FIG. 9 , the hatchway  338   a  may be located on the side of the device  300 . The hatchway  338   a  is preferably hinged and is not completely removable from the device  300 . As shown, the hatchway  338   a  may be opened to gain access to the reservoir  326 . 
   Alternatively, the hatchway  338   b  may be formed on the bottom of the device  300 . For example, as shown in  FIG. 10 , a substantially circular hatchway  338   b  is removable from the device  300 . In this configuration, the reservoir  326  is preferably coupled to the hatchway  338   b . By coupling the reservoir  326  thereto, the hatchway  338   b  supports the reservoir  326 , and, when assembled, ensures appropriate positioning of the wick  464  with respect to the atomizer assembly  308 . Specifically, when the hatchway  338   b  is removed, the wick  464  of the reservoir  326  is removed from contact with the atomizer assembly  308 . The reservoir  326  is then removed from the hatchway  338   b , a new reservoir  326  is coupled to the hatchway  338   b , and the hatchway  338   b  is reattached, with the reservoir  326  properly aligning with the atomizer assembly  308 . When the hatchway  338   b  of  FIG. 10  is used, it may be unnecessary for the horizontal platform  342  to support and to align the reservoir  326 , as the hatchway  338   b  will perform these functions. As such, the horizontal platform  342  will support the atomizer assembly  308 , either directly, or preferably, with the wire-like support  466  discussed above. 
   The chassis base  302   b  may also include one or more apertures  340  through which user control switches pass. A toggle switch  332 , for example, allows a user to turn on and off one or more of the active material emitter  308  and the LED&#39;s  306   a ,  306   b , and a slider switch  328  allows a user to adjust the rate at which active material is emitted from the active material emitter  308 . Alternatively or additionally, switches may also be provided that allow a user to adjust the light emission properties of the LED&#39;s  306   a ,  306   b , or to change an emitted light show. 
   Thus, the third embodiment provides a still further light and active material emitting device  300 . As with first and second embodiments described above, the device  300  may be configured to mimic the size and shape of a conventional candle. 
   As should thus be apparent, in each of the embodiments, a unitary housing comprises a device that emits both a flickering light and an active material, such as a fragrance, to the ambient air. As discussed above, the device is preferably inserted into a holder. Much like typical replaceable votive candles would be placed into decorative holders, unique holders are also provided for use with the lighting and active material devices disclosed herein. 
     FIG. 5  shows the device  100  of the first embodiment in a holder  104 . Specifically, the holder  104  has a globe-like shape, with a bottom, and an open top, similar to a conventional holder for a votive candle. The unitary housing comprising the combination of the chassis  102  and the base  134  is placed inside the holder  104 , through the open top of the holder  104 . Preferably, at least a portion of the holder  104  allows light to be emitted therethrough. FIGS.  11  and  12 A- 12 D show some representative alternative holder  304  configurations into which a light and active material emitting device  300  can be placed. These examples are by no means limiting. 
   When an active material emitter is used, the emitted active material should also be emitted from the holder, and it is thus preferred that the holder provide ample ventilation. In particular, the light and active material emitting device is preferably arranged in the holder such that the emission aperture through which the active material is dispensed is between about one inch and about six inches from the top of the holder and substantially away from the inner surface of the holder. With such an arrangement, buildup of active material on the inside of the holder is minimized. Moreover, the holder may be designed to aid the flow of the active material to the ambient environment. By tapering the holder such that the width of the holder narrows nearer the top of the holder, airflow will increase as it leaves the holder. Furthermore, it is preferred that the holder not impede the emission of light from the LED&#39;s in such an embodiment. Specifically, the unitary housing is preferably arranged in the holder such that the tip (as used in the first and third embodiments, discussed above) is between about one-half of one inch and about two inches from the holder, and preferably closer than one inch. The holder may also act as a diffuser. Furthermore, we envision that the holder could further include, for example, a fan for aiding in further dispersion of the active material emitted from the active material emitter. Optionally, a heater or other similar device may aid in dispersing the active material. Still further, convection may be used to disperse the active material, whereby an ambient temperature within the device is increased to a high enough level to aid in dispersing the active material. 
   The holder may comprise a single piece into which the housing is placed. Alternatively, as shown in  FIGS. 12A-12D , a holder  304  may also comprise a holder base  304   a  and a holder cover  304   b . More specifically, the device is contained within, or alternatively comprises, the holder base  304   a  that receives and supports the holder cover  304   b . The holder cover  304   b , when supported by the holder base  304   a , covers the tip  324 . That is, light emitted from the housing by the respective illumination devices also passes through the holder cover  304   b . Alternatively, the housing, e.g., the top  324 , may not diffuse emitted light, and only the holder cover  304   b  diffuses emitted light. 
   As a specific example of this embodiment, as shown in  FIG. 12A , a holder base  304   a  containing a unitary device as described above has a circumferential lip  304   c  extending radially outwardly from the holder base  304   a . At least a lower portion  304   d  of the holder cover  304   b  is sized so as to engage the lip  304   c  of the holder base  304   a , thereby resting the holder cover  304   b  on the holder base  304   a . Other illustrative examples of holders  304  are shown in  FIGS. 12B-12D . 
   While we envision that the holder cover  304   b  may rest on the holder base  304   a , it is preferable that the holder cover  304   b  detachably attach to the holder base  304   a . For example, the holder cover  304   b  may be designed to snap onto the holder base  304   a . Alternatively, the holder cover  304   b  and the holder base  304   a  may be designed such that the holder cover  304   b  is rotated onto the holder base  304   a , forming a locking engagement. In this or any configuration, the holder cover  304   b  may be relatively movable when secured to the holder base  304   a . Specifically, when the holder cover  304   b  is generally cylindrical, it may be rotatable on the holder base  304   a  to turn the LED&#39;s  306   a ,  306   b  and/or the active material emitter  308  on and off. Additionally, the engagement and disengagement of the holder cover  304   b  and the holder base  304   a  may act to turn the light source and/or active material emitter on and off. In this manner, the device would only operate with the holder cover  304   b  attached. Moreover, the holder cover  304   b  and holder base  304   a  may be specially designed such that only certain covers  304   b  can be used with the holder base  304   a . For instance, the holder base  304   a  may include a reader (not shown) that reads an ID (e.g., an RF tag) of the holder cover  304   b . In this manner, the device will not work unless the holder cover  304   b  has an appropriate ID. 
   When using the holder  304  according to this embodiment, we also envision that the holder cover  304   b  could emit an active material therefrom. For example, impregnable materials such as polyolefins are known that may be impregnated or infused with an active material, such as a fragrance. By forming the holder cover  304   b  of such a material, the holder cover  304   b  will emit an active material over time in addition to that emitted by the active material emitter  308 . Alternatively, the device of this embodiment could not include the active material emitter  308 , in which case, only the holder cover  304   b  will emit an active material. Also, with respect to the second embodiment described above, we note that the combination of chassis and base resembles a decorative candle, in which case a holder may not be desired. In such a case the base or chassis may be impregnated with an active material. 
   Because the holder cover  304   b  of this embodiment is removable, access to the device is facilitated (for example, to turn the LED&#39;s  306   a ,  306   b , on or off) and the holder cover  304   b  can be easily replaced. For example, when the active material, such as a fragrance, impregnated in the holder cover  304   b  is completely disseminated, a fresh, new holder cover  304   b  can easily be purchased and attached. Also, a user that has recently redecorated, or that wants to move the device to another room, may purchase a holder cover  304   b  having a certain color or other aesthetic feature. Moreover, replacement holder covers  304   b  may provide different smells. In other embodiments, the entire holder (or base) may be replaced. 
   A further embodiment of a light and active material emitting device  500  is illustrated in  FIGS. 15A-22 . Referring to  FIGS. 15A ,  15 B, and  17 , the device  500  generally includes a cover portion  504  and a base portion  506 . The base portion  506  generally includes a base  508  and a housing  510  disposed on the base  508  for enclosing control circuitry (described hereinafter) for the device  500 . A column  512  extends upwardly from the housing  510  and is preferably integral with the housing  510 . Further, an arm portion  514  extends perpendicularly from the column  512  and is integral with the column  512 . The arm portion  514  includes an active material dispenser in the form of an atomizer assembly  516  that extends through a center portion  518  thereof. The atomizer assembly  516  is described in greater detail with respect to  FIGS. 13 and 14 . 
   Any of the atomizer assemblies described in any of the patents incorporated by reference herein may be utilized as the atomizer assembly  516  (or as any of the atomizer assemblies described herein). In general, these assemblies apply an alternating voltage to a piezoelectric element to cause the element to expand and contract. The piezoelectric element is coupled to a perforated orifice plate  519 , which in turn is in surface tension contact with a liquid source. The expansion and contraction of the piezoelectric element causes the orifice plate to vibrate up and down whereupon liquid is driven through the perforations in the orifice plate and is then emitted upwardly in the form of aerosolized particles. 
   Preferably, a container  520  having an active material therein, preferably a liquid fragrance, is inserted into the active material dispenser adjacent the atomizer assembly  516  for emission of the active material therefrom. The container  520  is preferably inserted adjacent the atomizer assembly  516  as discussed in detail with respect to  FIGS. 8A-8C . The container  520  includes a wick  522  in communication with the active material therein and extending through a top portion thereof, wherein the wick  520  transports active material from the container  520  to the atomizer assembly  516 . 
   A cap  524  may disposed over the atomizer assembly  516  to hide the components of the atomizer assembly  516 . Preferably, as seen in  FIGS. 17 and 19 , the arm portion  514  includes a plurality of upwardly extending projections  526  extending therefrom, wherein outwardly extending projections  528  extend from the upwardly extending projections  526 . The outwardly extending projections  528  are adapted to engage an annular lip  530  extending from an inner periphery  532  of the cap  524  to secure the cap  524  over the atomizer assembly  516 . The cap  524  further includes a central circular aperture  534  therein such that active material emitted from the atomizer assembly  516  is directed through the aperture  534 . 
   Referring to  FIGS. 16-18 , the base portion  506  further includes a housing cover  540  disposed atop the housing  510 . As seen in  FIG. 18 , the housing cover  540  includes a plurality of downwardly extending projections  542 , wherein an outwardly extending projection  544  extends from a bottom portion  546  of each downwardly extending projection  542 . The housing  510  includes a plurality of cutout portions  547  in a top portion  548  thereof, wherein the downwardly extending projections  542  extend into the cutout portions  546  such that top portions  550  of the outwardly extending projections  544  engage an inner upper surface  552  ( FIG. 19 ) of the housing  510  to retain the housing cover  540  on the housing  510 . 
   As best seen in  FIG. 18 , the housing cover  540  further includes an upwardly extending column  554  that interfits with the column  512  extending from the housing  510  when the housing cover  540  is disposed on the housing  510  to form a channel  555 . Preferably, wires extending from the electrical components of the control circuitry to the atomizer assembly  516  are disposed in the channel  555  to hide and protect the wires. Also preferably, the columns  512 ,  554  are formed of a transparent or translucent material, preferably a clarified material, such as clarified propylene, so that the columns  512 ,  554  allow light to pass therethrough. Still further, the housing cover  540  includes a light control device  556 , such as a light diffuser, light pipe, lens, or the like, in a center portion  560  thereof, wherein the light control device  556  is preferably secured to or integral with the housing cover  540 . The light control device  556  generally includes a cavity  562  in a bottom portion  564  thereof, as best seen in  FIG. 19 . Various embodiments of light control devices  556  will be discussed in greater detail hereinafter. 
   As seen in  FIG. 19 , the base portion  506  of the device encloses control circuitry shown at  570 . In particular, the base  508  includes a support structure  572  extending upwardly therefrom that supports a printed circuit board (PCB)  574 . An LED  576  is operatively connected to and extends upwardly from a central portion  578  of the PCB  574 . As best seen in  FIGS. 20 and 21 , an emission frequency actuator arm  580  extends through a rectangular aperture  582  in a bottom portion of the base  508 . The emission frequency actuator arm  580  is operatively connected to a slide switch  583 , wherein the slide switch  583  is operatively connected to the PCB  574 . The actuator arm  580  preferably includes five selectable positions that control the emission frequency of the atomizer assembly  516 . Specifically, the slide switch  583  includes a button  584  extending therefrom that is movable along a slot  586  in the slide switch  583  to one of five detent positions. A yoke  588  extending from the actuator arm  580  surrounds the button  584  on sides thereof to move the button  584  along the slot  586 . Selection of a position by the user with respect to the actuator arm  580  moves the button  584  within the slot  586 , thereby indicating to the slide switch  583  the current position of the actuator arm  580 . The positions of the slide switch  583  are detected by the PCB  574 . Components mounted on the PCB  574  control the atomizer assembly  516  corresponding to the position of the actuator arm  580 , wherein each of the positions correspond to different time intervals that define the dwell time or the time between subsequent emission of puffs of active material by the atomizer assembly  516 . As discussed above, wires extend from the PCB  574  to the atomizer assembly  516  to actuate the atomizer assembly  416  in dependence upon the position of the actuator arm  580 . 
   The PCB  574  further includes a switch  600  having a depressable button  602  extending upwardly therefrom. Depression of the button  602  turns the LED  576  on or off depending on the current state of the LED  576 . The actuation of the button  602  and the operation of the control circuitry  570  will be discussed in greater detail hereinafter. 
   As noted above, the housing  510  encloses the PCB  574  and other control circuitry and the LED  576 . When the housing cover  540  is attached to the housing  510 , as discussed in detail above, the LED  576  is disposed in the cavity  562  located at the bottom portion  564  of the light control device  556 , such that light emitted from the LED  576  may be reflected and refracted by the light control device  556 . 
   Referring to  FIG. 21 , the base portion  506  of the device  20  includes a battery door  620  that includes a hinge  622  at a first end  624  thereof and a latching mechanism  626  at a second end  628  thereof. The latching mechanism  626  interacts with a locking recess  630  in the base portion  506  to hold the battery door  620  in a closed position. The latching mechanism  626  may be flexed to release the latching mechanism  626  from the locking recess  630 , such that the battery door  620  may pivot about the hinge  622  to open the battery door  620  and allow access to a battery compartment  631 . 
   As further seen in  FIG. 19 , the base portion  506  of the device  500  includes two batteries  640  that preferably provide direct current that is converted into high-frequency alternating current power that is selectively applied to the atomizer assembly  516  and the LED  576 . Optionally, the device  500  may be powered by alternating household current, which is rectified, converted to high-frequency alternating current power, and reduced in voltage and applied intermittently to the atomizer assembly  516  and/or the LED  576 . The batteries  640  may be any conventional dry-cell battery such as “A”, “AA”, “AAA”, “C”, and “D” cells, button cells, watch batteries, and solar cells, but preferably, the batteries  640  are “AA” or “AAA” cell batteries. Although two batteries are preferred, any number of batteries that would suitably fit within the device  500  and provide adequate power level and service life may be utilized. 
   The base portion  506  may further include optional feet  642  extending therefrom to aid in stabilizing the active material emitting device  500 . Although four feet  642  are depicted, any suitable number of feet  642  for stabilizing the device  500  may be utilized. 
   Referring to  FIG. 22 , the cover portion  504  includes a lower cylindrical wall  650  having a first diameter and an upper cylindrical wall  652  having a second diameter that is preferably smaller than the first diameter. An angled wall  654  joins the lower cylindrical wall  650  to the upper cylindrical wall  652 . The cover portion  504  further includes a circular top wall  656  adjacent the upper cylindrical wall  652  and having a circular aperture  658  disposed in a central portion thereof. 
   As seen in  FIGS. 19 and 22 , the cover portion  504  is positioned over the base portion  506  during use of the device  500 . Specifically, the cover portion  504  includes first and second apertures  660   a ,  660   b  disposed opposite one another in a periphery  662  of the lower cylindrical wall  650 . The base portion  506  includes first and second spring clips  664   a ,  664   b , as seen in  FIG. 17 , extending from opposing sides of the housing  510 . Each of the spring clips  664   a ,  664   b  includes a protrusion  666   a ,  666   b , respectively, extending outwardly therefrom. In use, the cover portion  504  is placed over the base portion  506  such that the upper cylindrical wall  652  surrounds the column  512 , the arm portion  514 , and the atomizer assembly  516 , and the lower cylindrical wall  650  abuts an outer wall  668  of the housing  510 . The cover portion  504  is further positioned over the base portion  506  such that the atomizer assembly  516  is aligned with the aperture  658  in the top wall  656  of the cover portion  504 . The aperture  658  provides an outlet for active material that is atomized by the atomizer assembly  516  and emitted from the device  500 . As the cover portion  504  is placed over the base portion  506 , the spring clips  664   a ,  664   b  are pressed inwardly by the user. Once the apertures  660   a ,  660   b  in the lower cylindrical wall  650  are aligned with the protrusions  666   a ,  666   b  extending from the spring clips  664   a ,  664   b , the user may release the spring clips  664   a ,  664   b . As the spring clips  664   a ,  664   b  are released, the protrusions  666   a ,  666   b  move outwardly into the apertures  660   a ,  660   b . Walls  670   a ,  670   b  defining each of the protrusions  666   a ,  666   b , respectively, thereby interfere with walls  672   a ,  672   b  defining the respective aperture  660   a ,  660   b  to prevent removal of the cover portion  504  from the base portion  506 . If the user desires to remove the cover portion  504 , the user may press inwardly on the spring clips  664   a ,  664   b  and remove the cover portion  504 . 
   As best seen in  FIG. 22 , the cover portion  504  further includes an annular ring  680  extending downwardly from an intersection of the upper cylindrical wall  652  and the angled connecting wall  654  of the cover portion  504 . As seen in  FIG. 18 , the housing cover  540  includes a plurality of spring fingers  682  in part defined by slots  684  that extend inwardly from a periphery  686  of the housing cover  540 . Each of the spring fingers  682  includes a projection  688 , as best seen in  FIG. 18 , extending downwardly therefrom. The annular ring  680  rides on top of the spring fingers  682 , which are resilient and act as flexures biased upwardly. Thus, as seen in  FIGS. 15A and 15B , the cover portion  504  is biased in a position such that a upper surfaces  692   a ,  692   b  of the protrusions  666   a ,  666   b  are spaced from upper walls  694   a ,  694   b  of the apertures  660   a ,  660   b  to create gaps  690   a ,  690   b  therebetween. The gaps  690   a ,  690   b  allow movement of the cover portion  504  in a vertical direction relative to the housing  510 . A user may therefore exert downward pressure on the cover portion  504  against the bias of the resilient spring fingers  682  that act as flexures. Such pressure allows the cover portion  504  to move downwardly until the upper surfaces  692   a ,  692   b  of the protrusions  666   a ,  666   b  of the spring clips  664   a ,  664   b  abut the upper walls  694   a ,  694   b  respectively, of the apertures  660   a ,  660   b . As the cover portion  504  moves downwardly, the annular ring  680  flexes the spring fingers  682  downwardly. As the spring fingers  682  move downwardly, one of the projections  688  extending downwardly from the spring fingers  682  that is aligned with the depressable button  602  contacts the depressable button  602 , thereby activating the switch  600 . A change in state of the switch  600  is detected by the PCB  574  and the LED  576  is turned on (for a predetermined timeframe) or off depending on the current state of the LED  576 , as described in greater detail hereinafter. 
   The cover portion  504  is preferably made of a transparent or translucent material, such as glass and/or a polymeric resin, such that the cover portion  504  functions as a light diffuser. All or portions of an inner surface  696  and/or an outer surface  698  of the cover portion  504  may include a surface treatment, such as a frosted surface, a coating, a roughened surface, a textured surface, and/or the like, in order to provide an even dispersion of light through the cover portion  504 . Optionally, one or more of a lower portion  699  ( FIG. 19 ) of the housing  510  or the lower cylindrical wall  650  of the cover portion  504  may include a decal or other obscuring element thereon in order to prevent the electronics of the device  500  from being viewed from outside the device  500 . Still optionally, a decal or other obscuring element may be positioned on the upper cylindrical wall  652  of the cover portion  504 . 
   As seen in  FIGS. 23 and 24 , the active material emitting device  500  may be placed into a container  700  for use thereof, or may be placed on a surface and used alone. The container  700  also preferably acts as a light diffuser and may be made of a transparent or translucent material, such as glass and/or a polymeric resin. All or portions of an inner surface  702  and/or an outer surface  704  of the container may include a surface treatment, such as a frosted surface, a coating, a roughened surface, a textured surface, and the like, to provide relatively even dispersion of light through the container  700 . Optionally, one or more images may be formed on the container  700  by placing a sticker  705  or other image-forming device (such as a decal) on a surface thereof. Still optionally, etchings may be formed in the light control device  556  to project a shape or shadow, as desired. 
   Although one shape of container is depicted herein, any shape of container is contemplated, as long as the device  500  fits sufficiently therein. 
   Referring to  FIG. 24 , the active material emitting device  500  is disposed within the container  700  such that the feet  642  of the device  500  rest upon an upper surface  706  of a bottom portion  708  of the container  700 . Preferably, the device  500  fits within the container  700  without portions of the lower or upper cylindrical walls  650 ,  652  touching the inner surface  702  of the container  700 . 
   As further seen in  FIG. 24 , the top wall  656  of the housing cover  540  is preferably aligned with an annular rim  720  disposed at a top portion  722  of the container  700 . Optionally, the top wall  656  of the housing cover  540  may be disposed at, slightly below, or above the annular rim  720 . During operation of the device  500  within the container  700 , the device  500  emits liquid from the container  520  into the air surrounding the container  700  by means of the atomizer assembly  516 . The greater the vertical distance is between the top wall  656  of the housing cover  540  and the annular rim  720 , the greater the distance is between the atomizer assembly  516  and the annular rim  720 . When the distance between the atomizer assembly  516  and the annular rim  720  is too great, an effect called “fallout” may occur. When active material is emitted by the atomizer assembly  516 , it must be emitted upwardly a distance great enough to allow the transient air flow of the surroundings to carry the active material throughout the surroundings. When the top wall  656  of the housing cover  540  is disposed too far below the annular rim  720 , the active material is not emitted by the atomizer assembly upwardly a distance great enough for this to occur. Thus, the active material falls downwardly without being carried throughout the surroundings, thereby causing the active material to fall into the container, onto the housing cover  540 , and onto a surrounding surface. This “fallout” effect prevents the device  500  from efficiently dispersing active material into the surroundings and also creates a potentially undesirable accumulation of material. For this reason, it is also necessary to orient the atomizer assembly  516  and the LED  576  such that the atomizer assembly  516  is disposed above the LED  576  in order to prevent “fallout.” In one embodiment, to prevent fallout, the orifice plate  519  of the atomizer assembly  516  is disposed 0.25 inch (6.35 mm) or less from the annular rim  720  of the container  700 . 
   Other features in addition to or in place of the positioning of the orifice plate  519  of the atomizer assembly  516  with respect to the annular rim  720  of the container  700  are possible. For example, apertures may be disposed in the container  700  to increase air flow within the device and therefore carry the emitted active material into the air surrounding the container  700 . Another feature might include increasing the time for which the active material is emitted, and thereby increasing the inertia created by the active material and increasing the amount of active material that is carried away from the device into the air surrounding the device. 
   Any light emitted upwardly from the LED  576  along a longitudinal axis  730  of the device  500  is blocked from exiting the device  500  by the atomizer assembly  516  and container  520  due to the positioning of such components above the LED  576 . The light control device  556  that is disposed above and around the LED  576  is provided to reflect and/or refract light that is emitted from the LED  576 . Most of the light that is emitted upwardly along the longitudinal axis  730  is reflected and/or refracted by the light control device  556  and emitted from the device  500  radially outwardly through a central portion thereof. As seen in  FIG. 23 , this positions the light around a center portion  740  of the container  700  and device  500 , instead of near a top portion  742  thereof. 
     FIGS. 25-31  depict various embodiments of light control devices that may be used with any of the embodiments as disclosed herein. The light control devices transmit light therethrough from a light receiving end to an opposite light dispersion end where a facet generally reflects a portion of the transmitted light laterally, or radially outwardly, as seen in  FIG. 25  and may transmit a portion therethrough. These embodiments are suitable for use in various light apparatuses alone and/or in combination with other light pipes and/or light diffusers. The light pipes of  FIGS. 25-31  are preferably made of a transparent or translucent material suitable for transmitting light from the light receiving end to the light dispersion end, such as glass and/or a polymeric resin. A preferred material for the light control devices is a clarified propylene. Although the cross-sections of such light pipes are depicted as being circular, other non-circular cross-sections are possible. 
   Referring to  FIG. 25 , a light pipe  1000  extends along a longitudinal axis  1002  between a light receiving end  1004  having a cavity  1006 , such as a cylindrical bore, disposed therein and a light dispersing end  1008  having a reflective facet  1010  disposed therein. The cavity  1006  is sized to receive a light source, such as an LED  1012 . The light pipe  1000  has substantially smooth or polished first and second exterior surfaces  1014 ,  1016 , defining first and second cylindrical portions  1018 ,  1020 , wherein the first portion  1018  has a diameter greater than a diameter of the second portion  1020 . The first cylindrical portion  1018  also has a height that is preferably greater than a height of the second cylindrical portion  1010 . A tapered exterior surface  1022  defines a frustoconical portion  1024  that is disposed between the first and second exterior surfaces  1014 ,  1016  and the first and second cylindrical portions  1018 ,  1020 . The reflective facet  1010  includes a conical depression extending across and into the light dispersion end  1008  through the second cylindrical portion  1018  and into the frustoconical portion  1024 . The conical depression of the facet  1010  forms a reflective surface  1026  that is angularly displaced from the longitudinal axis  1002  so as to disperse most of the transmitted light as indicated by light rays  1027  from the LED laterally, or radially outwardly, as seen in  FIG. 25 . 
     FIGS. 26-28  are three variations of another embodiment of a light pipe  1030  that extends along a longitudinal axis  1032  between a light receiving end  1034  having a cavity  1036 , such as a cylindrical bore, disposed therein and a light dispersing end  1038  having a reflective facet  1040  disposed therein. The cavity  1036  is sized to receive a light source, such as an LED  1042 . The light pipe  1000  has substantially smooth or polished first and second exterior surfaces  1046 ,  1048  defining first and second cylindrical portions  1050 ,  1052 , wherein the first portion  1050  has a diameter greater than a diameter of the second portion  1052 .  FIGS. 26-28  depict three variations of the same embodiment wherein the diameters of the first and second portions  1050 ,  1052  are varied to receive different light dispersion results. Specifically, the first and second portions  1050 ,  1052  of  FIG. 27  have the smallest diameters and the first and second portions  1050 ,  1052  of  FIG. 28  have the largest diameters whereas the first and second portions  1050 ,  1052  of  FIG. 26  have diameters intermediate the diameters of the corresponding portions  1050 ,  1052  of  FIGS. 27 and 28 . Differences in diameter of the first and second portions  1050 ,  1052  alter a height along the longitudinal axis  1032  and a diameter of the reflective facet  1040  at the light dispersing end  1038 . 
   Still referring to  FIGS. 26-28 , a rounded exterior surface  1054  defining a shoulder portion  1056  is disposed between the first and second exterior surfaces  1046 ,  1048  and the first and second cylindrical portions  1050 ,  1052 . The reflective facet  1040  includes a conical depression that forms a reflective surface  1058  that is angularly displaced from the longitudinal axis  1032  so as to disperse most of the light transmitted from the LED laterally, or radially outwardly, as depicted in  FIG. 25 . 
   The light pipe  1070  of  FIG. 29  extends along a longitudinal axis  1072  and includes a reflective facet  1080  having the same shape as the light pipe  1000  of  FIG. 25 , except that a reflective facet  1080  only extends through a second cylindrical portion  1090  and does not extend into a third portion  1094 . Further, the heights of first and second cylindrical portions  1088 ,  1090  are substantially equal or nearly so, instead of one being greater than the other. 
   Referring to  FIG. 30 , a light pipe  1120  extends along a longitudinal axis  1122  between a light receiving end  1124  having a cavity  1126 , such as a cylindrical bore, disposed therein and a light dispersing end  1128  having a reflective facet  1130  similar to that discussed with respect to  FIG. 25 . The cavity  1126  is sized to receive at least one light source, such as an LED  1132 , therein. The cavity  1126  is defined by a cylindrical side wall  1131  and a curved top wall  1133  that extends into the cavity  1126 . The light pipe  1120  has substantially smooth or polished first and second exterior surfaces  1134 ,  1136  defining first and second cylindrical portions  1138 ,  1140 , wherein the first portion  1138  has a diameter greater than a diameter of the second portion  1140 . A rounded exterior surface  1144  defining a shoulder portion  1146  connects the first and second exterior surfaces  1134 ,  1136  and the first and second cylindrical portions  1138 ,  1140 . 
   As seen in  FIG. 30 , the reflective facet  1130  only extends through the second portion  1140  and does not extend into the shoulder portion  1146 . The reflective facet  1130  further forms a reflective surface  1150  that is angularly displaced from the longitudinal axis  1122  to disperse most of the light transmitted from the LED laterally, or radially outwardly, as seen in  FIG. 25 . 
   The embodiment of  FIG. 31  is similar to that of  FIG. 30 . The light pipe  1120  of  FIG. 31  differs in that the light pipe  1120  includes a single cylindrical exterior surface  1160  having a substantially constant diameter throughout. 
   In the embodiments of  FIGS. 25-31 , the LED is connected to a PCB of a light apparatus in which it is disposed in order to power and control the LED. Although embodiments of light pipes herein are depicted as having a relatively small dimension along a longitudinal axis, this dimension may be increased or decreased as necessary to create the necessary light dispersions. 
   Although the embodiments of  FIGS. 25-31  are described as having smooth surfaces defining the respective light pipes, roughened or textured surfaces may also be utilized. 
   The operation of the active material emitting device  500  of  FIGS. 15A-24  will now be described in detail. When a user desires to operate the device  500 , the battery door  620  is opened using the latching means  626  and batteries  640  are placed within the battery component  555 . To insert a container  520  having an active material therein, the cover portion  504  is removed from the device  500 , as described in detail above, an old container  520  is removed and/or a new container  520  is inserted, and the cover portion  504  is placed back onto the device  500 , as described in detail above. The order of insertion of the batteries  640  and a container  520  may be reversed, but as soon as both are inserted, the device  500  begins emitting the active material. 
   The user may then move the actuator arm  580  ( FIG. 21 ) to set the dwell time for emission of the active material. Once the dwell time is set, the device  500  may be placed in a container  700 . It is not until the user depresses the cover portion  504 , as described in detail above, that the LED  576  will turn on. The LED  576  can be turned off by a subsequent depression of the cover portion  504  or the LED  576  will automatically shut off after a predetermined time period, such as three hours or four, as described in greater detail below. 
     FIG. 32  illustrates a programmable device in the form of an application specific integrated circuit (ASIC) 2000 that operates in conjunction with further electrical components to control the energization of any of the LED&#39;s described above and, optionally, any of the active material emitters or atomizer assemblies described above (each of the emitters and atomizer assemblies is referred to as an active material dispenser hereinafter). If desired, the ASIC 2000 may be replaced by a microprocessor, any other programmable device or a series of discrete logic and electronic devices. In general, in one mode of operation, the ASIC 2000 operates only a single LED 2 , such as the LED  576 , or any of the other LED&#39;s described above, such that LED 2  appears to flicker. If two independently operable LED&#39;s are present, the ASIC 2000 operates the LED&#39;s such that a further LED 1  appears to be continuously energized and LED 2  appears to flicker. If desired, this arrangement could readily be modified by one of ordinary skill in the art such that LED 1  appears to flicker and LED 2  appears to be continuously energized. In a still further embodiment, LED 1  and LED 2  could be operated in a non-independent fashion such that both are caused to appear to flicker or appear to be continuously energized. Still further, in the illustrated embodiment, if the ASIC 2000 is connected to and independently operates both LED 1  and LED 2 , circuitry internal to the ASIC 2000 for operating the active material dispenser is disabled and the active material dispenser is omitted. Alternatively, in those embodiments where two or more LED&#39;s are to be operated together (i.e., not independently, such as LED  1  and LED  2  discussed above), the ASIC 2000 could be modified in a manner evident to one of ordinary skill in the art given the disclosure herein such that disabling of the active material dispenser circuitry does not occur and the active material dispenser can be connected to the ASIC 2000 and be operated thereby. Also, while in the illustrated embodiment the active material dispenser is operable by the ASIC 2000 only when one or two LED&#39;s are connected thereto, the ASIC 2000 could be modified by one of ordinary skill in the art such that the ASIC 2000 can operate an active material dispenser as described above even when no LED is connected to the ASIC 2000. 
   In the preferred embodiment, LED 1  and LED 2  are operated in a pulse-width mode (PWM) of operation. Specifically LED 1 , when used, is provided a high frequency PWM waveform that results in the appearance that LED 1  is continuously energized. The duty cycle for the PWM waveform and the frequency for the PWM waveform are fixed. Regardless of whether LED 1  is used, LED 2  is energized to obtain the flickering effect by utilizing a pseudo random number generator  2002  (shown in block diagram form in  FIG. 32  and shown functionally in  FIG. 33 ) in conjunction with PWM value tables  2004  and one or more of a plurality of timers  2006  to establish a duty cycle for operation of LED 2  (the PWM value tables  2004  and the timers  2006  form a digital portion of the ASIC 2000). The pseudo random number generator  2002  is functionally shown in  FIG. 33  as a series of three NOR gates G 1 , G 2 , and G 3  coupled to particular bit positions of a sixteen-bit shift register SR. The initial value of the generator  2002  is  3045  (hexadecimal). The waveform generation processes to obtain the flickering effect for single LED operation and dual independent LED operation are described in greater detail below. 
   Referring again to  FIG. 32 , the ASIC comprises control apparatus including a charge pump and average current source  2008 , a PWM switch  2010  for LED 1 , and a PWM switch  2012  for LED 2 . A capacitor C 1  is coupled across terminals CP 1  and CP 2  and stores charge from the batteries  640  and charge pump  2008  to permit continued operation of LED 1  (if used) and LED 2  even when the output voltage of the batteries  640  falls below the voltage required to turn on such LED(s). The light emitting diode LED 2  is coupled across terminals CP 1  and LED 2  whereas the light emitting diode LED 1  (if used) is coupled across terminals CP 1  and LED 1 . 
   The ASIC 2000 receives power from the batteries  640 , which, as noted above, may be a pair of series-connected conventional AA 1.5 v cells, at terminals VCC and VSS 1 . A capacitor C 2  is coupled across the terminals VCC and VSS 1  for filtering purposes. Preferably, the terminal VSS 1  is connected to ground potential. A boost converter  2014  of the ASIC 2000 in conjunction with a capacitor C 3 , a Schottky diode D 1 , and an inductor L 1  all external to the ASIC 200 and coupled to terminals VDD, BOOST, and VCC provide a supply voltage at the terminal VDD. In the event that the active material dispenser circuitry is not utilized, the diode D 1 , the inductor L 1 , and the capacitor C 3  are omitted and the terminal VDD is directly coupled to the terminal VCC and the BOOST terminal is left unconnected. The ASIC 2000 further receives a signal at an ON_OFF terminal from a switch S 1  (that preferably comprises the switch  600  of  FIG. 20 ) that is in turn coupled to ground. The ASIC 2000 includes an internal debouncer (not seen in  FIG. 32 ) that debounces the signal developed by the switch S 1 . 
   The ASIC 2000 further includes a clock oscillator  2016  that serves as an internal clock for the ASIC 2000, a power-on reset circuit  2018  that resets various parameters upon energization of the ASIC 2000, and an undervoltage detector  2020  that disables the ASIC 2000 when the battery voltage drops below a particular level. A voltage/current reference circuit  2021  assists in determining when to activate the charge pump for the LED&#39;s and is a reference for when to disable the ASIC 2000 as the batteries  640  discharge. The VCO  2023 , in turn, receives a ramp voltage developed on a terminal CSLOW by a ramp oscillator  2024 . The ramp oscillator  2024  and the VCO  2023  control the active material dispenser, when used, as noted in greater detail hereinafter. 
   Still further in the preferred embodiment, the digital portion of the ASIC 2000 further includes a system controller in the form of programmed logic  2026  that executes programming to control the LED&#39;s, an eight-bit address register  2027 , and an address pointer register  2028 . The digital portion further includes a 64×8 programmable read only memory (PROM)  2029 , a PROM controller  2030 , and a digital controller  2031 , all of which generate drive signals for the LED(s). As noted in greater detail hereinafter, in the case where both LED 1  and LED 2  are used, the value developed by the address pointer register  2028  at any particular time is equal to the value developed by the address register  2027  at that time with the second and third least significant bits removed from the eight-bit value developed by the address register  2027  and the remaining more significant bits shifted toward the least significant bit. For example, if the value developed by the address register  2027  at a particular time is 01101100, then the output value of the address pointer register  2028  at that time is 011010. Similarly, if the current output value of the address register  2027  is 10101001, 00001110, or 10011111, then the current output value of the address pointer register  2028  is 101011, 000010, or 100111, respectively. In the case where only LED 2  is used, the value developed by the address pointer register  2028  at any particular time is equal to the six least significant bits of the value developed by the address register  2027  at that time. 
   Referring next to  FIG. 34 , a series of waveform diagrams illustrate operation of the circuitry of  FIG. 32  under the assumption that LED 1  and LED 2  are connected as shown in  FIG. 32 . If, on the other hand, LED 1  is omitted, the illustrated waveforms for LED 2  remain the same, whereas no current is supplied to the LED 1  terminal of the ASIC 2000. Also, the flicker pattern for LED 2  is different when LED 1  is not used as compared to when LED 1  is used, in the manner and for the reasons described hereinafter. 
   The waveform diagram labeled MODE of  FIG. 34  reflects the operation of the ASIC 2000 in response to various conditions including the open/closed state of the switch S 1 . The terminal ON_OFF has an internal pull-up feature such that when the switch S 1  is open, as seen in  FIG. 32 , the voltage VDD is supplied to the debouncer (the debouncer is implemented by the system controller  2026 ). When the switch S 1  of  FIG. 32  is closed, a low state signal in the form of ground potential is supplied to the debouncer, as reflected in the transition between one and zero states in the ON_OFF signal illustrated in  FIG. 34 . Upon release of the switch S 1 , a transition occurs from the zero to one states of the ON_OFF signal. The ASIC 2000 then enters an on condition mode at a time t 1  provided that the debouncer received the zero state signal for at least a predetermined period of time, such as 25 milliseconds. During operation in the on mode, the LED(s) is (are) energized, as noted in greater detail hereinafter. When the switch S 1  is momentarily closed then opened at a time t 2  for at least the predetermined period of time, the ASIC 2000 enters a sleep mode of operation, during which only the debouncer is active so as to retain the capability of detecting momentary closure of the switch S 1  for at least the predetermined period of time. Thereafter, closure and opening of the switch S 1  at a time t 3  for at least the predetermined period of time causes the ASIC 2000 to reenter the on mode. 
   Following the time t 3 , if the switch S 1  is not actuated within a predetermined delay period (referred to hereinafter as the “auto shut-off delay period”), the ASIC 2000 automatically enters the sleep mode, as represented at time t 4 . This auto shut-off delay period is variable depending upon whether the active material dispenser or LED 1  are not used. Specifically, if a terminal GDRV is not connected to ground, but instead is connected to external circuitry that implements the active material dispenser, as discussed in detail hereinafter, the predetermined delay period is set equal to three hours. Otherwise, the predetermined delay period is set equal to four hours. A subsequent momentary closure and opening of the switch S 1  at a time t 5  causes the ASIC 2000 to again enter the on mode. 
   At a time t 6  the power provided to the ASIC 2000 is interrupted, such as by removal of one or more of the batteries  640 . Upon reapplication of power to the ASIC 2000 at a time t 7 , a power-on reset mode is entered wherein values used by the ASIC 2000 are initialized. Thereafter, the ASIC 2000 enters the sleep mode until the switch S 1  is again momentarily closed and opened at time t 8 . Following the time t 8 , the ASIC 2000 remains in the on mode until the auto shut-off delay period has expired, or until the switch S 1  is momentarily closed, or until the voltage developed by the batteries  640  drops below a particular level, such as 1.8 volts, as illustrated at time t 9 . 
   As seen in the waveform diagrams illustrated as APPARENT_LED 1  and APPARENT_LED 2 , LED 1  (when used) is operated such that it appears to be continuously on whereas the LED 2  is operated such that it appears to flicker with a pseudo random flicker pattern. With regard to LED 2 , a number of frames of equal duration are established wherein each frame includes a number of pulse cycles therein. Preferably, each pulse cycle is 4.3 milliseconds in length and 24 pulses are included per frame. Accordingly, each frame is 103 milliseconds in duration. Also preferably, the pulse on-times for a particular frame are all equal in duration, resulting in a particular average current magnitude for that frame. Also preferably, the pulse-widths in adjacent frames are different so as to provide an average current different from the particular average current magnitude to provide the flickering effect. The choice of the pulse-widths for the frames is controlled by the pseudo random generator  2002  and entries in one of two portions of the PWM value table  2004 . When LED 1  is used in conjunction with LED 2 , a first portion of the PWM value table  2004  is accessed. On the other hand, when LED  1  is not used, a second portion of the PWM value table  2004  is accessed. 
   As illustrated in the bottom three waveforms of  FIG. 34 , the waveforms ACTUAL_LED 1  and ACTUAL_LED 2  indicate the drive waveforms applied to LED 1  and LED 2 , respectively, under the assumption that both LED&#39;s are used. (The scale of the waveforms ACTUAL_LED 1  and ACTUAL_LED 2  is greatly expanded relative to the scale of the waveforms APPARENT_LED 1  and APPARENT_LED 2 .) In general, LED 1  and LED 2  are operated intermittently at a high frequency so as to provide the appearance that the LED&#39;s are being operated at a constant intensity level over a period of time. More particularly, between a time t 10  and a time t 12 , the LED 1  receives two pulses of current, as does the LED 2 . Specifically, in a first one-sixth of a total of two cycles between the times t 10  and t 12 , neither LED 1  nor LED 2  receives a current pulse. In a second one-sixth of the two cycles the LED 2  receives a pulse of current whereas the LED 1  does not. In a third one-sixth of the two cycles the LED 1  receives a current pulse whereas the LED 2  does not. In a fourth one-sixth of the two cycles (wherein the second cycle begins at a time t 11 ) neither the LED 1  nor the LED 2  receives a current pulse while in a fifth one-sixth of the two cycles LED 1  receives a current pulse whereas the LED 2  does not. Finally, in a sixth one-sixth of the two cycles the LED 2  receives a current pulse whereas the LED 1  does not. 
   Thereafter, the above-described cycle pairs repeat until the combined voltage developed by the batteries  640  drops below the voltage required to adequately energize LED 1  and LED 2 . At this point, the charge pump  2008  is actuated to provide sufficient forward voltage to LED 1  and LED 2 . Specifically, LED 1  and LED 2  receive the current pulses as described previously and the charge pump  2008  is turned on during the first one-sixth and fourth one-sixth of cycle pair to charge the capacitor C 1  of  FIG. 32 . The capacitor C 1  thereafter provides sufficient voltage to LED 1  and LED 2  to maintain adequate drive thereto. Preferably, the drive pulses for LED 1  and LED 2  have a 45 milliamp peak current and a typical pulse-width of about 4.2 microseconds. If desired, these values may be changed to obtain different LED intensities. 
   Referring next to the flowchart of  FIGS. 35A and 35B , which illustrate the overall operation of the ASIC 2000 in accordance with the waveforms of  FIG. 34  (with the exception of the bottom three waveforms thereof), control begins at a block  2040 , which checks to determine when a POWER-ON RESET signal has been developed. This signal is generated when batteries are first placed into the active material emitting device, or when dead batteries are replaced with charged batteries, or when charged batteries are removed from the device and are returned to the device and a minimum supply voltage has been reached. 
   Control then passes to a block  2042 , which implements a reset mode of operation whereby all internal registers are set to define start-up values and all timers are reset. A block  2044  then checks to determine whether a minimum supply voltage has been reached and, when this is found to be the case, control passes to a block  2045 A, which checks to determine whether the terminal LED  1  is connected to ground potential. If this is found to be the case, a block  2045 B disables the PWM switch  2010 , enables the PWM switch  2012 , and selects a particular table of the PWM value tables  2004  corresponding to single LED operation for subsequent accessing. On the other hand, if the block  2045 A determines that the terminal LED 1  is not connected to ground (i.e., the terminal is coupled to LED 1 ) control bypasses the block  2045 B and proceeds to a block  2045 C, whereupon both PWM switches  2010  and  2012  are enabled and a different table of the PWM value tables  2004  corresponding to two LED operation is selected for later accessing. Control from the blocks  2045 B and  2045 C passes to a block  2046 , which then implements a sleep mode of operation. During operation in the sleep mode, all internal components of the ASIC 2000 are deactuated, with the exception of the debouncer, which remains active to determine when the switch S 1  is momentarily depressed for greater than the particular period of time. 
   Following the block  2046 , control pauses at a block  2048  until a determination has been made that the switch S 1  has been momentarily depressed and released. When this action is detected, and it has been determined that the terminal LED 1  is not connected to ground, a block  2049 B turns LED 1  on in the fashion described above so that such LED appears to be continuously energized. Conversely, if it has been determined that the terminal LED 1  is connected to ground, the block  2049 B is skipped. Control then passes to a block  2050 , which initializes the pseudo random generator  2002  of  FIG. 33  and causes the pseudo random generator  2002  to develop a sixteen-bit pseudo random number at the output of the shift register SR of  FIG. 33  of which the eight least significant bits are loaded into the address register  2027  of  FIG. 32 . This loading, in turn, causes the address pointer register  2028  to develop a six-bit number corresponding to the eight-bit pseudo random number loaded into the register  2027  as described above. 
   Following the block  2050 , a block  2052  reads one of 64 PWM values stored in the selected table of the PWM value tables  2004  of  FIG. 32 . In general, the PWM values stored in the selected PWM value table define duty cycles for LED 2 . Preferably, PWM values that are stored in adjacent locations in the selected table have no particular relationship with one another (i.e., the PWM values in adjacent storage locations vary in a random or pseudo random manner from one another), although this need not be the case. In any event, the block  2052  reads the PWM value from the selected table stored at the address identified by the six-bit current output value of the address pointer register  2028 . A block  2054  then multiplies the PWM value read by the block  2052  by a particular length of time, such as 16.8 microseconds, and loads that multiplied PWM value into a PWM-LED 2 _ON timer implemented as a part of the timers  2006  of  FIG. 32 . 
   Following the block  2054 , a block  2056  of  FIG. 35B , turns on LED 2  and starts the PWM-LED 2 _ON timer and also initializes and starts 103 msec. and 4.3 msec. timers. Assuming at this point that the batteries  640  are fully charged, the charge pump portion of the circuit  2008  is inactive. Control then pauses at a block  2058  until the PWM-LED 2 _ON timer  2006  experiences an overflow condition. When this overflow condition occurs, a block  2060  turns off LED 2  for the balance of the 4.3 millisecond pulse cycle and resets the PWM-LED 2 _ON timer. Control then passes to a block  2062  which determines whether the switch S 1  has been momentarily pressed and released. If not, a block  2064  determines whether the shut down timer that measures the auto shut-off delay period has experienced an overflow condition. If this is also not the case, a block  2066  checks to determine whether a 103 millisecond PWM-frame timer implemented as a part of the timers  2006  of  FIG. 32  has experienced an overflow condition. If this is further not the case, control remains with a block  2068  until a 4.3 millisecond PWM pulse cycle timer also implemented as a part of the timers  2006  experiences an overflow condition, whereupon control returns to the block  2056  to begin the next 4.3 millisecond PWM pulse cycle. 
   If the block  2062  determines that the switch S 1  has been momentarily pressed and released, or if the block  2064  determines that the shut down timer has experienced an overflow condition, control returns to the block  2046  of  FIG. 35A  whereupon the sleep mode is entered. 
   If the block  2066  determines that the 103 millisecond PWM-frame timer has overflowed, control passes to a block  2070 , which either increments or decrements the address register  2027 . The decision to increment or decrement the address pointer is determined by the most significant bit of the sixteen-bit pseudo random number developed by the pseudo random generator  2002 . A zero as the most significant bit causes the block  2070  to decrement the address register  2027 , whereas a one as the most significant bit causes the block  2070  to increment the address register  2027 . If desired, the decision to increment or decrement may be based upon another bit of the pseudo random number, or a zero in a particular bit position may cause the block  2070  to increment the address register  2027  while a one in the particular bit position may cause the block  2070  to decrement the address register  2027 . As a still further alternative, the block  2070  may only decrement or only increment the address register  2027  for each pseudo random number developed by the generator  2002  regardless of the values of the bits of the pseudo random number. Still further, the particular bit that determines whether to increment or decrement may vary from number-to-number developed by the generator  2002 . In any event, the address pointer may be incremented when a particular pseudo random number has been developed by the generator  2002  and the address pointer may be decremented (or incremented, for that matter) when a subsequent pseudo random number is developed by the generator  2002 . 
   Following the block  2070 , a block  2072  checks to determine whether the address pointer register  2028  has experienced an overflow condition. Specifically, because 64 values are stored in the selected table of the tables  2004 , the block  2072  checks to determine whether the incrementing or decrementing of the address pointer  2070  has caused the address pointer register  2028  to increment to a value of 0000010 or to decrement to a value of 111111. If this is not the case, a block  2074  reads the PWM value at the next memory location (either above or below the previous memory location) defined by the current value of the address pointer register  2028 . A block  2076  multiplies the PWM value stored at the memory location with the particular length of time (i.e., 16.8 microseconds) and loads the multiplied value into the PWM-LED 2 _ON timer and control passes to the block  2056  of  FIG. 35B  to start a new 4.3 millisecond pulse cycle. 
   If the block  2072  determines that the address pointer register  2028  has experienced an overflow condition, a block  2080  checks to determine whether an under voltage condition has been detected whereby the battery voltage has fallen below a particular level of, for example, 1.8 volts. If this is found to be the case, control passes to a block  2086  that causes the ASIC 2000 to enter a low battery sleep mode of operation. The block  2086  maintains the ASIC 2000 in the low battery sleep mode until a power-on reset condition again occurs, for example, by replacing the discharged batteries with fully charged batteries. This action prevents the discharged batteries from being further discharged to a point where operation of the device can no longer be maintained or to a point where the batteries may leak and damage the device. 
   If the block  2080  determines that the under voltage condition has not been detected, a block  2082  causes the pseudo random generator  2002  of  FIG. 33  to generate a new sixteen-bit pseudo random number and the address register  2027  is loaded with the eight least significant bits of this new number by a block  2084 . Control then passes to the block  2052   FIG. 35A . 
   In the case where LED 1  is used, the foregoing methodology of ignoring two of the eight bits of the pseudo random number when addressing the selected table results in a pattern of repetitively addressing two consecutive memory locations in the table  2004  a total of four times. That is, in the example where the pseudo random number is 00000000 and the block  2070  is incrementing, the memory location addressing scheme proceeds as follows: 
                                                  000000   000010   000100           000001   000011   000101           000000   000010   000100           000001   000011   000101           000000   000010   000110           000001   000011   000111           000000   000100   .           000001   000101   .           000010   000100   .           000011   000101                        
The foregoing addressing scheme when both LED 1  and LED 2  are used results in a flickering effect while that is visually pleasing while allowing the use of a relatively small PWM value table for the two LED mode of operation. This, in turn, reduces the cost of the ASIC 2000. It should be noted that the single LED mode of operation does not result in the repetitive addressing scheme noted above; rather, in this case, incrementing and decrementing occur directly through the selected table.
 
   Referring again to  FIG. 32 , the ASIC 2000 includes a terminal ILIM in addition to the terminals CSLOW and GDRV that are connected to external circuitry to implement the active material dispenser. Specifically, a capacitor C 4  is connected between the terminal ILIM and ground. A pair of inductors L 2  and L 3  and a piezoelectric element  3000  are connected in series with one another across the capacitor C 4 . A gate electrode of a transistor Q 1  is coupled to the terminal GDRV and source and drain electrodes of the transistor Q 1  are coupled to a tap of the inductor L 2  and ground, respectively. A further capacitor C 5  is coupled between the terminal CSLOW and ground. 
   The system logic  2026  continuously operates the active material dispenser if the terminal GDRV is not connected to ground. (This determination, as well as the determination of whether LED 1  is coupled to the ASIC 2000 is performed by a detector  3002 ,  FIG. 32 .) The operation of the active material dispenser is independent of the operation of the LED(s). A rate selector switch S 2  (that preferably comprises the switch  583  of  FIG. 20 ) provides inputs to terminals SW 1 , SW 2 , SW 4 , and SW 5  that together determine the duration of the dwell periods between discharges of the active material dispenser. Specifically, as seen in  FIG. 36 , the rate selector switch S 2  is diagrammatically shown as including a housing  3010 , a movable switch contact  3012  having an internal electrically conductive wiper  3014  and an externally-disposed slide button  3016 . A first electrically conductive trace  3018  extends fully at least along a series of first through fourth switch positions P 1 -P 4 , and possibly extends as shown to a fifth switch position P 5 . The first trace  3018  is electrically connected to ground potential. Second through fifth electrically conductive traces  3020 ,  3022 ,  3024 , and  3026 , are connected to terminals SW 5 , SW 4 , SW 2 , and SW 1 , respectively, of the ASIC 2000. The terminals SW 1 , SW 2 , SW 4 , and SW 5  have internal, controllable pull-ups and pull-downs. When the ASIC 2000 is in the sleep mode, these terminals are all pulled down. Conversely, when the ASIC 2000 is checking the status of the signals provided to these terminals, the terminals SW 1 , SW 2 , SW 4 , and SW 5  are pulled up internally. The rate selector switch S 2  pulls down one of these terminals depending upon the position P 1 -P 5  that the switch contact  3012  is moved to. When the switch contact  3012  is in the position P 1  as illustrated in  FIG. 36 , the terminal SW 5  is pulled down to ground potential, and the ASIC 2000 establishes the dwell time at a first value, such as 5.75 seconds. When the switch contact  3012  is moved in the direction of the arrow  3030  to any of the positions P 2 , P 4 , and P 5  one of the terminals SW 4 , SW 2 , or SW 1 , respectively, is pulled down to ground potential, and the ASIC 2000 establishes the dwell time at other values, such as 7.10, 12.60 or 22.00 seconds, respectively. When the switch contact  3012  is moved to the position P 3 , none of the terminals SW 1 , SW 2 , SW 4 , and SW 5  is pulled down to ground potential, and the ASIC 2000 establishes the dwell time at a further value, such as 9.22 seconds. In the event that more than one of the terminals SW 1 , SW 2 , SW 4 , and SW 5  is coupled to ground at any particular time due to a switch malfunction, the dwell time is preferably established at a mid-range value, such as 9.22 seconds. 
   The ramp oscillator  2024  obtains the output of the clock oscillator  2016  and develops the ramp voltage on the terminal CSLOW, as noted above. The ramp oscillator  2024  continuously runs if the detector  3002  determines that the terminal GDRV is connected to other than ground potential, and the output of the ramp oscillator  2024  acts as a clock to control the pumping frequency (in accordance with the setting of the switch S 2 ) and the pump duration. Preferably, the pump duration is established at a constant value of about 11 milliseconds. The frequency of the ramp oscillator  2024  is determined by the size of the capacitor C 4  and the charging/discharging current for the capacitor C 4  is obtained from a bias current generated by the ASIC 2000. The bias current is trimmed in order to meet the frequency tolerance requirements of the ramp oscillator  2024 .  FIG. 37  functionally illustrates the ramp oscillator  2024  as comprising an op amp  3040  connected in a comparator configuration and having a noninverting input coupled to the capacitor C 5  and further coupled to switches S 3  and S 4 . The switches S 3  and S 4  are operated in antiphase relationship each with a 50% duty cycle to alternately connect constant current sources  3042  and  3044  to the capacitor C 5 . An inverting input of the op amp  3040  is coupled to a switch S 5 , which alternately connects voltages V thrup  and V thrlo  to the inverting input.  FIG. 38  illustrates the resulting voltage V CSLOW  developed at the terminal CSLOW of the ASIC 2000. The voltage V CSLOW  linearly ramps up and down between limits V thrup  and V thrlo  with a period equal to 1/f slow  where f slow  is the frequency of the waveform developed by the clock oscillator  2016 , typically about 1000 Hz. 
   The capacitor C 4  is charged by a constant current source  3050  ( FIG. 32 , labeled “Ilimiter”). The constant current source  3050  is switched off in a slowly decreasing manner when the voltage VDD is outside a regulated range thereof. 
   The VCO  2023  is controlled by the ramp voltage developed by the ramp oscillator  2024  during a pumping operation such that the frequency of the drive voltage developed at the terminal GDRV increases from a lower value to an upper value. This operation is illustrated in the waveform diagram of  FIG. 39 , which illustrates that the VCO output voltage comprises a series of pulses each having rise and fall times t r  and t f , respectively, and pulse-widths t p1 , t p2 , . . . , t p(N-1) , t pN , each measured from the beginning of a rise time to the beginning of a fall time of the pulse. The frequency of the VCO output voltage linearly increases from a first frequency f low  to a second frequency f high , where f low  is preferably equal to about 130 kHz and f high  is preferably equal to about 160 kHz. Also preferably, the duty cycle is maintained at about 33% throughout the variation in VCO output voltage frequency. 
   Referring next to the state diagram of  FIG. 40 , when a power-on-reset condition is sensed, all of the internal registers of the ASIC 2000 (including registers that are used for operation of the LED(s)) are set to defined start up values and the ASIC 2000 enters a state S 1 . While in the state S 1  the logic  2026  ( FIG. 32 ) checks to determine if the terminal GDRV is coupled to ground. If so, the shut down timer implemented as part of the timers  2006  of  FIG. 32  is set to four hours and control passes to a state S 2 , at which the active material dispenser functionality is disabled. On the other hand, if the logic  2026  determines that the terminal GDRV is not coupled to ground, the fragrance dispenser is functionality enabled, and control passes to a state S 3  comprising a fragrance sleep mode of operation. As control passes to the state S 3 , the terminals SW 1 , SW 2 , SW 4 , and SW 5  are pulled up and a duration for the fragrance sleep mode is read in by establishing the position of the switch S 2 . During the fragrance sleep mode of operation, the terminal GDRV is pulled down to a low voltage level, the VCO  2023  is disabled, and the terminals SW 1 , SW 2 , SW 4 , and SW 5  are pulled down. 
   Once the fragrance sleep mode duration has elapsed, the ASIC 200 enters a state S 4  where the terminal GDRV is maintained at a low voltage, the VCO  2023  is powered up, the terminals SW 1 , SW 2 , SW 4 , and SW 5  are pulled up and read, and the under voltage detector  2020  is checked. The ASIC 2000 then enters a state S 5  during which the active material dispenser is energized in accordance with the setting of the switch S 2  for 11 milliseconds, as described above The ASIC 2000 remains in the state S 5  until the 11 milliseconds have elapsed and thereafter re-enters the sleep mode at state S 3 . Control then continues to cycle among the states S 3 , S 4 , and S 5  until the under voltage detector  2020  determines that the battery voltage drops below a particular level, at which time the active material dispenser functionality is disabled until another power-on-reset condition is sensed, whereupon control reverts to the state S 1  and the foregoing operation is again undertaken. 
   It should be noted that at all times other than during a pumping operation the VCO  2023  is maintained in an off condition. 
     FIG. 41  illustrates a circuit  3998  for controlling a piezoelectric actuator  4000  and a light emitting diode LED 3 . The circuit includes a programmable integrated circuit U 3 , which may be in the form a microprocessor of the type ATTINY 13V-10331 manufactured by Atmel. The microprocessor U 3  may be programmed in accordance with the flowchart of  FIGS. 35A ,  35 B to operate in the various modes and to obtain a flickering effect of LED 3 , with the exception that the microprocessor U 3  does not include the capability to operate multiple LED&#39;s independently. Accordingly, in the illustrated embodiment the microprocessor U 3  also lacks the ability to determine if multiple LED&#39;s are connected thereto, although the microprocessor can be programmed to include these capabilities, if desired. 
   The microprocessor U 3  may also be programmed to read a switch S 2 , which may comprise the rate selector switch  583  of the embodiment of  FIGS. 15A-24 , and operate the piezoelectric actuator  4000  generally in accordance with the state diagram of  FIG. 40  so that the various operational modes described in connection therewith are implemented. As described in greater detail hereafter, the piezoelectric actuator  4000  forms a part of a resonant circuit that is operated at a resonant frequency by the microprocessor U 3 . 
   An example of a piezoelectric actuator drive circuit that is operated at a resonant frequency is disclosed in Blandino et al. U.S. application Ser. No. 11/464,419, filed Aug. 14, 2006, entitled “Drive Circuits and Methods for Ultrasonic Piezoelectric Actuators,” the disclosure of which is hereby incorporated by reference herein. 
   Specifically, the microprocessor U 3  is, in turn, responsive to the setting of the rate selector switch S 2 , which can be set to one of five settings. A wiper W of the switch S 2  can be connected to one of five pins  2 - 6  of the switch S 2 . The pin  2  is disconnected from all sources of potential whereas pins  3 - 5  are connected to three resistors R 12 , R 13 , and R 14  forming a voltage divider with a resistor R 11 . When the wiper W is connected to pin  2 , the input to a pin  7  of the microprocessor through the resistor R 11  is not divided. The pin  6  is coupled to ground potential. The setting of the switch S 2  determines the duration of a dwell period during which the piezoelectric actuator is not actuated. The dwell periods are separated by emission sequences preferably of fixed duration. Preferably, the emission sequence is about 12 mS in length and the dwell periods are selectable to be about 5.75 seconds, 7.10 seconds, 9.22 seconds, 12.60 seconds, or 22.00 seconds in length. In other embodiments, these dwell periods are selectable to be about 9.22 seconds, 12.28 seconds, 17.92 seconds, 24.06 seconds, or 35.84 seconds in length or 5.65 seconds, 7.18 seconds, 9.23 seconds, 12.81 seconds, or 22.54 seconds in length. Any emission sequence duration and any dwell period durations could be used and the number of selectable dwell period durations and multiple selectable emission sequence durations of any number could be implemented. The pin  7  of the microprocessor U 3  is coupled to the wiper W and is further coupled by the resistor R 11  to a line  4002  that receives a voltage VPP developed by a voltage regulator U 2  and provided to a pin  8  of the microprocessor U 3 . The pin  8  of the microprocessor U 3  is further coupled by a capacitor C 18  to ground potential. The voltage on the pin  7  of the microprocessor U 3  is sensed by an internal A/D converter of the microprocessor to read the setting of the switch S 2 . 
   Alternatively, the dwell period(s) may be predetermined to be anywhere in a range from 12 mS up to 30 minutes or longer. For example in a boost mode (which may be selected by a switch (not shown)), when it is desired to release a large amount of fragrance, each emission sequence could be 12 mS and each dwell period could be 12 mS in duration to achieve a 50% duty cycle. On the other extreme, when the room in which the volatile dispensing device is located is unoccupied (for example, as detected by a motion sensor or other sensor(not shown)) it might be desirable to emit volatile for a 12 mS duration once every 30 minutes just to maintain some volatile in the room. As noted in greater detail hereinafter, this periodic emission of volatile at a selectable rate may be overridden by a command to emit volatile at an accelerated rate on a periodic or aperiodic basis. 
   A pin  1  of the microprocessor U 3  is coupled by a resistor R 10  to the regulated voltage developed on the line  4002  developed by the voltage regulator U 2 . A switch S 6  is further coupled between the pin  1  of the microprocessor U 3  and ground potential, wherein the switch S 6  may comprise the switch  583  of the embodiments of  FIGS. 15A-24 . A pin  3  of the microprocessor U 3  is coupled by a resistor R 9  to a DC source  4003 , which may comprise two series-connected 1.5 volt AA alkaline batteries. Also, a parallel combination of a resistor R 15  and a capacitor C 11  is coupled between the pin  3  of the microprocessor U 3  and ground potential. A pin  4  of the microprocessor U 3  is coupled to ground potential. 
   The voltage regulator U 2  is coupled to the DC source  4003  and preferably develops a regulated voltage of 3.3 volts. A further voltage regulator U 1  and components L 1 A, D 1 A, C 2 A, C 5 A, R 2  and R 3  together produce a regulated voltage of preferably 12 volts on a line  4004 . Capacitors C 3 A and C 7  smooth the voltage on the line  4004 . 
   The circuit  3998  further includes four transistors Q 1 A and Q 2 -Q 4  coupled in a full-bridge configuration between the line  4004  and ground potential. The resonant circuit comprising an inductor L 3 A and the piezoelectric actuator  4000  is coupled across junctions  4006 ,  4008  between drain electrodes of the transistors Q 1 A, Q 2  and Q 3 , Q 4 , respectively. Resistors R 1  and R 17  are coupled between the line  4004  and gate electrodes of the transistors Q 1 A and Q 3 , respectively. Capacitors C 6  and C 12  are coupled between the gate electrodes of the transistors Q 1 A, Q 2  and Q 3 , Q 4 , respectively. 
   First and second current sensors in the form of resistors R 16  and R 18  are coupled between source electrodes of the transistors Q 3  and Q 4 , respectively, and the line  4004  and ground potential, respectively. Feedback capacitors C 13 , C 15 , and C 16  are coupled between the source electrodes of the transistors Q 3  and Q 4  and a feedback line  4010 . A feedback signal developed on the feedback line  4010  is AC coupled and phase shifted for proper operation of a control circuit  4012 . 
   The control circuit  4012  includes an amplifying and inverting circuit  4014  and a driver circuit  4016 . The amplifying and inverting circuit  4014  includes first and second NAND gates  4018 ,  4020 , respectively. The first NAND gate  4018  is biased into a linear range of operation by a negative feedback resistor R 4  to operate as an amplifier and the second NAND gate  4020  is used as an inverter. A first input of the first NAND gate  4018  receives a gating or enable signal developed on a line  4022  developed at a pin  5  of the microprocessor U 3 . The line  4022  is coupled by a resistor R 6  to ground potential. A second input of the first NAND gate  4018  receives the signal on the feedback line  4010 . 
   When power is supplied to the microprocessor U 3  by the DC source  4003  the microprocessor U 3  periodically develops an approximate 12 mS gating or enable signal at the pin  5 . The gating or enable signal is delivered to the first input of the NAND gate  4018 . An output of the NAND gate  4018  is coupled to first and second inputs of the NAND gate  4020  and an output of the NAND gate  4020  is coupled by a capacitor C 14  back to the second input of the NAND gate  4018 . The capacitor C 14  supplies a small amount of positive feedback to promote stable transitions. The output of the NAND gate  4018  is coupled to a first input of a third NAND gate  4032  and the output of the NAND gate  4020  is coupled to a first input of a fourth NAND gate  4034 , wherein the NAND gates  4032 ,  4034  together comprise the driver circuit  4016 . Second inputs of the NAND gates  4032 ,  4034  receive the gating or enable signal on the line  4022 . The control circuit  4012  causes the NAND gates  4032 ,  4034  to drive the pairs of transistors Q 1 A, Q 2  and Q 3 , Q 4  by providing drive signals to the gate electrodes thereof. In this regard, the NAND gate  4020  acts as an inverter to invert the output of the NAND gate  4018  so that the transistors Q 1 A and Q 2  are driven 180° out of phase with respect to the transistors Q 3  and Q 4 . That is, the transistors Q 1 A and Q 4  are first turned on while the transistors Q 2  and Q 3  are held in an off condition, and subsequently the transistors Q 1 A and Q 4  are turned off and the transistors Q 2  and Q 3  are turned on. The sequence of conduction then repeats. Preferably, the transistors are operated at about 50% duty cycle. If desired, a period of time may be interposed between turn-off of one pair of transistors and turn-on of another pair of transistors during which all transistors are briefly turned off to prevent cross-conduction. In any event, the current through the piezoelectric actuator  4000  alternates at a selected resonant frequency thereof during each gating period (i.e., during the times that the gating or enable signal is developed) dependent upon the impedance of the resonant circuit comprising the inductor L 3 A and the piezoelectric actuator  4000 . This oscillation occurs in a continuous fashion during each approximate 12 mS emission sequence, following which the microprocessor U 3  terminates the gating or enable signal on the pin  5  thereof, thereby turning off the transistors Q 1 A-Q 4  and terminating further emission of active material by the piezoelectric actuator  4000 . 
   When a user wishes to activate the circuitry during operation referred to as a “boost” mode, the user depresses a switch (not shown) coupled to the microprocessor U 3 . This action causes the microprocessor U 3  to develop the gating or enable signal on the pin  5 . In one embodiment, the gating signal is periodically or aperiodically developed during an interval. For example, the gating signal may cause volatile emission comprising one 12 mS pulse every second for 83 or 84 seconds. As another example, the gating or enable signal may cause volatile emission comprising a group of ten 12 mS pulses spaced apart from one another by 72 mS, wherein successive groups of ten 12 mS pulses take place at intervals of 60 seconds. This sequence may continue for any length of time. As should be evident, any number of pulses of any duration can be periodically or aperiodically emitted at any desired frequency (if periodic) and over one or more intervals of any length, as desired. In yet another embodiment, the gating or enable signal is developed for as long as the switch S 6  is depressed so that volatile is emitted in a continuous fashion during the entire time that the switch S 6  is depressed. In any event, the piezoelectric actuator  4000  oscillates at the particular resonant frequency during the entire time that the gating signal is developed, although the actuator  4000  may be intermittently actuated during the time that the gating or enable signal is developed, if desired. 
   A pair of diodes D 3 A, D 3 B are provided to limit the maximum voltage across the resistor R 16  and a pair of diodes D 4 A, D 4 B limit the maximum voltage across the resistor R 18 . Limiting the maximum voltage across the current sensing resistors R 16 , R 18  increases the efficiency of the circuit. Furthermore, the circuit  3998  includes first and second level shifting circuits to convert the 0-3.3 volt drive signal from the control circuit  4012  to approximately 9.3-12.3 volts to properly drive the transistors Q 1 A and Q 3 . A combination of a diode D 2 A, resistor R 1 , and capacitor C 6  forms the first level shifting circuit and a combination of a diode D 2 B, resistor R 17 , and capacitor C 112  forms the second level shifting circuit. 
   The microprocessor U 3  develops a pulse width modulated (PWM) waveform at a pin  6  that is supplied through a resistor R 24  to a non-inverting input of an operational amplifier (op amp)  4040 . The non-inverting input is further coupled by a parallel combination of a resistor R 25  and a capacitor C 20  to ground potential. The resistor R 25  and the capacitor C 20  together with the resistor R 24  comprise a voltage divider and filtering circuit. A first input of an AND gate  4042  receives a further gating or enable signal developed by the microprocessor U 3  and a second input of the AND gate  4042  is coupled by resistor R 20  to an output of the op amp  4040 . A capacitor C 19  is coupled between an output of the AND gate  4042  and the second input thereof. The output of the AND gate  4042  is further coupled by an inverter  4044 A and a resistor R 23  to the second input thereof. The AND gate  4042  together with the capacitor C 19 , the inverter  4044 A, and the resistor R 23  operate as an oscillator with positive feedback provided by the capacitor C 19  and negative feedback supplied by the inverter  4044 A and the resistor R 23 . This oscillator produces a PWM output that has a duty cycle varied by the output of the op-amp  4040 . The AND gate  4042  receives the regulated 3.3 V power developed by the voltage regulator U 2  and is further coupled to ground potential. 
   The PWM output of the inverter  4044 A is further coupled to a series of five inverters  4044 B- 4044 F that are coupled together in parallel and which together act as a drive circuit. An inductor L 4  receives the combined outputs of the inverters  4044 B- 4044 F in the form of a rectangular wave and smoothes the output voltage developed thereby to a substantially DC voltage level dependent on the duty cycle of the PWM output developed by the oscillator including AND gate  4042 , capacitor C 19 , inverter  4044 A, and resistor R 23 . The resulting waveform is applied to LED 3 , wherein the current amplitude delivered to LED 3  determines the brightness thereof. A current sensing resistor R 21  is coupled between LED 3  and ground potential and a feedback signal is supplied to an inverting input of the op amp  4040  by a resistor R 22  that is coupled to the junction between LED 3  and the resistor R 21 . A capacitor C 17  is coupled between the inverting input of the op amp  4040  and an output thereof. The resistor R 22 , capacitor C 17 , and op amp  4040  together act as an integrator that samples the voltage across resistor R 21  and uses negative feedback to force the sampled voltage at the inverting input of the op amp  4040  to equal the voltage delivered to the non-inverting input thereof as developed by the microprocessor U 3 , the resistors R 24  and R 25 , and the capacitor C 20 . The resulting output of the op-amp  4040  is a varying DC voltage level that causes LED 3  to flicker. The microprocessor U 3  implements a pseudo-random number generator and further stores PWM values in memory locations similar or identical to the programming illustrated in  FIGS. 35A and 35B  to produce the waveforms as seen in  FIG. 34 . 
   In an alternative embodiment (not shown), a microprocessor or ASIC may include a digital to analog converter, which can supply a DC drive signal to the integrator along with the feedback signal developed across the resistor R 21 . In this embodiment, the filtering circuit including resistors R 24 , R 25  and capacitor C 20  may be omitted. 
   The inverters  4044 A- 4044 F may be provided as a single integrated circuit and together comprise a low resistive output device that reduces on-resistance losses. 
   The oscillator comprising the AND gate  4042 , the capacitor C 19 , the resistor R 23  and the inverter  4044 A differs from known oscillators in that known oscillators utilize two inverter sections with a positive feedback applied across both sections and a negative feedback applied across one section. 
   The oscillator in  FIG. 41 , on the other hand, generates a PWM signal utilizing a non-inverting section and an inverting section with positive feedback applied across the non-inverting section and negative feedback applied across both the inverting and non-inverting sections. In the preferred embodiment, the capacitor C 19  provides the positive feedback and the resistor R 23  provides the negative feedback. The use of positive capacitive feedback and negative resistive feedback in this manner results in an oscillator that is more stable when switching between high and low states and prevents or substantially prevents unwanted oscillations at transitions between states. The frequency of oscillation is determined by the equivalent RC time constant as determined by the values of the capacitor C 19  and the parallel combination of the resistors R 23  and R 20 . 
   The time constant of the integrator formed by the op amp  4040 , the resistor R 22  and the capacitor C 17  preferably dominates the feedback loop to prevent instability of the circuit. 
   The rectangular waveform delivered to the inductor L 4  switches between ground potential and 3.3V at several hundred kilohertz. The inductor L 4  smoothes the rectangular waveform into an approximately constant waveform. The LED turn on voltage is approximately 1.9 volts; therefore, the PWM duty ratio of the oscillator output cannot exceed approximately 57% (i.e., 1.9/3.3) at the maximum brightness level so that LED 3  is not overdriven. The current limiting feature afforded by the inductor L 4  eliminates the need for a current limiting resistor that would simply dissipate the difference between the supply voltage of 3.3V and the turn on voltage of 1.9V of LED 3 . Such an approach using a current limiting resistor would reduce the efficiency of the circuit to 57% at best. The inductor L 4  simply circulates the current into and out of the power supply and does not dissipate same, thereby improving efficiency. The voltage regulator U 2  is approximately 95% efficient. The efficiency of the LED driver circuit of the illustrated embodiment approaches 95% as well, resulting in a total LED drive efficiency of 85%-90%. 
     FIG. 42  illustrates programming executed by the microprocessor U 3  to control the energization of the light emitting diode LED 3  according to one embodiment. The programming begins following power up of the circuitry by the DC power source  4003  at a block  4050 , which initializes various registers in the microprocessor U 3 . A block  4052  then reads the setting of the switch S 2  and a block  4054  periodically or aperiodically actuates the piezoelectric actuator  4000  in accordance with the setting of the switch S 2  as described above. A block  4056  then checks to determine whether the switch S 6  has been momentarily actuated a first time. If this is not the case control returns to the blocks  4052  and  4054 . Once the block  4056  determines that the switch S 6  has been actuated a first time, a block  4058  energizes LED 3  in accordance with the flickering sequence discussed above. 
   A block  4060  then checks to determine whether the switch S 6  has been momentarily actuated a second time. If this is found to be the case, LED 3  is turned off by a block  4062  and control returns to the block  4052 . On the other hand, if the block  4060  determines that switch S 6  has not been actuated, a block  4064  checks an internal timer of the microprocessor U 3  to determine whether a particular period of time, such as three hours, has expired since the switch S 6  was first momentarily actuated. If the particular period of time has not yet expired, control returns directly to the block  4052 . However, if the block  4064  determines that the particular period of time has expired, control passes to the block  4062 , which turns LED 3  off and control returns to the block  4052 . 
   Referring next  FIG. 43 , a flowchart of programming executed by the microprocessor U 3  is illustrated to implement an alternative embodiment. Control begins at a block  4100  which determines whether a power up reset has occurred caused by insertion of the batteries comprising the DC source  4003  or whether the switch S 6  has been momentarily actuated. If control passed to the block  4100  due to a power up reset, a block  4102  initializes internal components as well as variables, timers, etc. in the microprocessor U 3 . In particular, the block  4102  initializes various internal components of the microprocessor U 3  by, for example, setting up the processor clock, defining microprocessor pins as inputs or outputs, setting up an internal A/D converter (i.e., number of channels, conversion time, and A/D reference voltage), setting up the internal timer for the appropriate interrupt rate, initializing the PWM stage, etc. A block  4104  then checks to determine whether a cycle timer implemented by the microprocessor U 3  has expired. The cycle timer determines the dwell period between actuations of the piezoelectric actuator  4000 . If the cycle timer has expired, a block  4106  checks to determine whether the combined voltages of the batteries forming the DC source  4003  is greater than a predetermined level. If this is not found to be the case, a block  4108  turns off the LED and terminates further actuation of the piezoelectric actuator  4000 . In addition, the microprocessor U 3  is halted. 
   If the block  4106  determines that the combined battery voltages exceed a predetermined level, a block  4110  reads the position of the switch S 2  and reinitializes the value of the cycle timer to a value determined by the position of the switch S 2 . The piezoelectric actuator is then actuated for a 12 mS emission sequence. 
   Following the block  4110 , a block  4112  checks to determine whether an LED timer (described hereinafter) has expired. If this found to be the case, a block  4114  turns the LED off and control returns to the block  4104 . On the other hand, if the LED timer has not expired, a block  4116  determines whether an LED flicker timer has expired. In the illustrated embodiment, the LED flicker timer measures 108 mS frame intervals during which the LED is provided a constant duty cycle PWM waveform (in general, as noted above, the duty cycles are different from frame interval to frame interval to obtain the flickering effect). If this is not found to be the case, control returns to the block  4104 . Otherwise, a block  4118  causes the microprocessor U 3  to output a new LED brightness value. This is accomplished in the manner described above in connection with  FIGS. 35A and 35B  by accessing a next or different portion of a memory containing brightness values. The block  4118  also reloads the flicker timer with a value corresponding to 108 mS and control returns to the block  4104 . 
   If the block  4104  determines that the cycle timer has not expired, control by-passes the blocks  4106 - 4110  and proceeds directly to the block  4112 . If control passed to the block  4100  due to momentary actuation of the switch S 6 , a block  4120  toggles a register indicating whether the LED is to be turned on or off. A block  4122  determines whether the LED is to be turned on, in which case a block  4124  reloads the LED timer with a value corresponding to a predetermined duration, such as three hours, and LED 3  is turned on. Control then passes to the block  4104 . 
   If the block  4122  determines that the LED is to be turned off, the LED timer is cleared and LED 3  is turned off at a block  4126  and control passes to the block  4102 . 
   INDUSTRIAL APPLICABILITY 
   The light and active material emitting device provides light and/or active material emitters. The device provides an overall desired aesthetic ambience in an area, such as a room. 
   Numerous modifications to the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention and to teach the best mode of carrying out same. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.