Abstract:
A dispenser has a container for a liquid, a vent opening to allow air into the container, a valve to control the admission of air into the container, and a dispensing opening for the liquid to be dispensed therefrom. The dispenser is mounted with the dispensing opening at the bottom. When the valve is closed, a pressure differential is created that prevents the liquid in the container from flowing out. Upon opening of the vent valve, the pressure differential is reduced and dispensing can continue. Such a dispenser can be used to dispense fluids of varying viscosities and even nonporous solids. In one embodiment of the invention, an infrared radiation emitter and an infrared radiation detector are arranged in such a manner that, when a hand is placed below the dispenser, radiation from the emitter impinges on the hand and is reflected to the detector. Upon sensing the reflected radiation, the detector causes the valve for the vent tube to open so that the pressure differential in the container is eliminated and the liquid can be dispensed. When the hand is withdrawn, the detector no longer senses radiation from the emitter and causes the valve for the vent tube to close reestablishing the pressure differential that stops the outflow of liquid. The dispensing opening is preferably in the form of an S-shaped tube to prevent dripping of the liquid, such as soap, when the valve is closed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a dispenser for flowable soap. 
     2. Description of the Prior Art 
     Most dispensers for flowable soap are currently manually operated, which means that the dispenser must be touched when soap is to be dispensed. Since it is unsanitary to touch the dispenser, it would be desirable to be able to obtain soap without touching the dispenser. 
     Accordingly, several automatic dispensers have been developed employing two distinct principles for delivering fluid from a reservoir. The first technique makes use of a pump, which can be solenoid operated, rotating-cam operated, or actuated by deformation of a flexible reservoir. Pumps are inefficient in this type of application because any change in the kinetic or potential energy of the fluid must be provided by the electrical source energizing the pump. 
     More efficient devices use gravity to provide the force necessary to move the liquid. Accordingly, another technique is to position an electrically actuated valve below the fluid reservoir. When the valve is opened, the fluid is forced through it by gravity. This design is necessarily inefficient because the aperture size of the valve must be adapted as a function of the viscosity of the fluid that must flow through it. Thus, larger apertures require more energy to open them. Therefore, a more efficient automatic-dispenser design would be desirable for reasons of economics and energy conservation. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to eliminate the need for touching a dispenser in order to dispense a liquid such as soap therefrom. 
     Another objective of the invention is a design for an automatic dispenser that is suitable for liquids of various viscosities. 
     Another goal is a dispenser that utilizes gravity as the motive force for the liquid being dispensed. 
     Still another goal is a dispenser that operates with increased efficiency regardless of the viscosity of the liquid being dispensed. 
     Another objective is a design that can be implemented efficiently and economically. 
     Still another object is a dispenser that prevents dripping of the dispensed liquid between uses. 
     The preceding objects, as well as others which will become apparent as the description proceeds, are achieved by the invention. 
     One aspect of the invention resides in a dispenser for a liquid, such as liquid soap. The dispenser comprises a container for a supply of soap, and the container is provided with at least one opening for discharging soap therefrom. The dispenser further comprises means for detecting objects at a spacing from the container, and means for controlling the passage of soap through the discharging opening. The controlling means has a first condition in which soap is free to pass through the discharging opening and a second condition in which the passage of soap through the opening is inhibited. The controlling means is designed to assume the first condition in response to the detection of an object by the detecting means and to revert to the second condition in response to discontinued detection of the object. The detecting means can detect a hand which is spaced from the dispenser and is designed so that soap is dispensed when a hand is detected. Hence, the dispenser in accordance with the invention makes it unnecessary to touch the dispenser in order to obtain soap therefrom. 
     According to another aspect of the invention, the dispenser consists of a closed reservoir having a dispensing opening at its lower extremity through which the liquid can flow. As the fluid flows out of the reservoir through the opening, the pressure at the top in the reservoir is gradually reduced until the pressure differential between the inner top portion of the reservoir and the ambient, external atmospheric pressure is sufficient to stop the flow of fluid. An electrically actuated valve is positioned to admit air from outside the reservoir into the upper, low pressure, area of the reservoir to allow the fluid to flow from the reservoir through the lower opening. 
     Another aspect of the invention resides in a method of operating a soap dispenser. The method comprises the steps of placing an object at a predetermined location spaced from the dispenser, sensing the object while the object is at such location, and dispensing soap from the dispenser in response to the sensing step. The sensing step may include detecting energy reflected from the object, and the energy can comprise infrared radiation. The method can further comprise the steps of removing the object from the predetermined location, discontinuing the sensing step upon removal of the object from this location, and terminating the dispensing step in response to discontinuation of the sensing step. 
     The method may also comprise the step of inhibiting the dripping of soap from the dispenser subsequent to the terminating step. The dispenser can include a soap container and a supply of soap in the container, and the dispensing step may involve establishing communication between the soap supply and the atmosphere. 
     Additional features and advantages of the invention will be forthcoming from the following detailed description of preferred embodiments when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a dispenser according to the preferred embodiment of the invention. 
     FIG. 2 is a perspective view of a soap dispenser according to the invention in a holder. 
     FIG. 3 is a partly sectional perspective view of a soap reservoir constituting part of the soap dispenser of FIG.  2 . 
     FIG. 4 is a partially cut-out, enlarged perspective view of a cap constituting part of the soap dispenser of FIG.  2 . 
     FIG. 5 is a block diagram of circuitry for operating the soap dispenser of FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like parts are designated throughout with like numerals and symbols, FIG. 1 illustrates schematically a rigid reservoir  10  constructed with an opening  12  at the bottom and a sealed removable top  14 . The top is fitted with a small hose barb  16  that is connected to a valve  18  by a small tube  20  to admit air into the upper portion  22  of the reservoir. The opening  12  in the bottom of the reservoir  10  is preferably threaded to allow various dispensing nozzles, such as the S-shaped nozzle  24 , to be removably attached. The shape of the nozzle  24  is provided to inhibit post-dispense dripping as well as dripping due to atmospheric pressure variations. 
     The valve  18  is preferably a normally-closed miniature valve, such as the Clippard EE3-TL-12 Double E-3 Subminiature Electronic Valve made by Clippard Instrument Laboratory, Inc., of Cincinnati, Ohio. When open, the valve  18  admits air into the upper portion  22  of the reservoir, thereby allowing fluid in the reservoir to flow through the opening  12  and the nozzle  24 . As well understood in the art, the dispensing nozzle  24  can be constructed in a variety of internal diameters to achieve equal dispensing volumes for liquids with different viscosities. For a target dispensing time period and a given liquid volume in the reservoir, a variation in the kinematic viscosity of the liquid can be accounted for by the known relationship D 1 /D 2 =[v 1 /v 2 ] ¼ , where v 1  and v 2  are the kinematic viscosities of two alternative liquids and D 1  and D 2  are corresponding internal diameters for the dispensing nozzle. See Fox et al.,  Introduction to Fluid Mechanics , Wiley &amp; Sons (1985). 
     Upon receiving a dispense signal, the valve  18  is opened to admit air into the upper reservoir cavity  22 . In response, the liquid  26  contained in it begins to flow through the opening  12  and the dispensing nozzle  24 . The kinetic energy of the flowing liquid causes the upper reservoir cavity  22  to “overshoot” the equilibrium pressure differential required to just balance the liquid depth to stop the flow. Thus, the excess pressure differential causes the liquid to be “sucked back” into the reservoir such that the equilibrium position of the liquid-air interface  28  in the nozzle is drawn to the intermediate section of the S-shaped tube in the dispensing nozzle. It is understood that for the dispenser to drip, the liquid-air interface  28  would need to be in the outer section  30  of the tube in dispensing nozzle, which is no longer the case. Therefore, the combination of the nozzle design and the vacuum-controlled release of the liquid effectively prevents dripping when the valve  18  is closed. Similarly, atmospheric-pressure changes can cause the migration of the liquid-air interface  28  along the tube of the dispensing nozzle, but the dispenser can tolerate atmospheric-pressure reductions equal to the liquid head separating the current height of the interface  28  from the top of the intermediate section of the S-shaped tube in the nozzle  24 , as would be clearly understood by one skilled in the art. 
     Referring to FIG. 2, the numeral  110  identifies another embodiment of an automatic dispenser in accordance with the invention. The dispenser  110  is designed to dispense liquid soap in a flowable form and is especially well-adapted for that application. The soap dispenser  110  comprises a container  112  for holding a supply of soap. The container  112  includes a generally frustoconical reservoir or body  114  and a cover  116  which is removably mounted on one axial end of the reservoir  114 . The cover  116  can, for instance, be screwed onto the reservoir  114 , be a press fit on the reservoir or be held on the reservoir by suitable fasteners, such as screws. The soap dispenser  110  further comprises a lower cap or housing  118  which is removably mounted on the axial end of the reservoir  114  remote from the cover  116 . Similarly to the cover  116 , the cap  118  can, for example, be screwed onto, press fit, or held on the reservoir  114  by suitable fasteners. 
     FIG. 2 shows the soap dispenser  110  being supported in a holder  120 . The holder  120  includes a ring  122  having an inner diameter smaller than the maximum outer diameter of the reservoir  114  so that the reservoir can rest on the ring  122  when inserted in the latter. The holder  120  further includes a shank  124  which extends radially outward from the ring  122  and serves as a mounting element for the holder  120 . Thus, the shank  124  allows the holder  120  to be affixed to a surface such as a wall surface. The reservoir  114  accommodates a supply or body of soap  126 . Between the soap  126  and the cover  116  is an empty space  128  which is essentially airtight. 
     Turning to FIG. 3, the end of the reservoir  114  remote from the cover  116  is closed by a wall  130  which separates the interior of the reservoir  114  from the interior of the cap  118 . The wall  130  is provided with an opening  132  through which the soap  126  can be discharged from the reservoir  114 . The wall  130  is provided with a second opening  134  which is spaced from the discharging opening  132 . A vent tube  136  passes through the opening  134  and extends through the reservoir  114  as well as through the cap  118 . The vent tube  136  has opposite longitudinal ends  136   a  and  136   b  which are provided with apertures so that the vent tube  136  is open at either longitudinal end  136   a , 136   b . The longitudinal end  136   a  is located in the empty space  128  of the container  112 , and a check valve  138  is mounted in the longitudinal end  136   a . The check valve  138  prevents the soap  126  from flowing into the vent tube  136  if the container  112  should be tilted. 
     Considering the enlarged view of FIG. 4, a valve  140  is mounted inside the cap  118  at the longitudinal end  136   b  of the vent tube  136 . The valve  140  is preferably a miniature valve such as described above. The valve  140  has an open condition or open position in which the valve establishes communication between the interior of the vent tube  136  and the atmosphere. The valve  140  also has a closed condition or closed position in which the interior of the vent tube  136  is sealed from the atmosphere. 
     In the open condition of the valve  140 , the space  128  in the container  112  communicates with the atmosphere by way of the vent tube  136  and is at atmospheric pressure. The soap  126  is then free to flow out of the container  112  via the discharging opening  132 . When the valve  140  is subsequently placed in the closed condition, a vacuum is produced in the space  128  and causes the soap  126  to stop flowing out of the container  112 . The vent tube  136  and valve  140  can thus be considered to constitute a means for controlling the passage of the soap  126  through the discharging opening  132 . 
     The cap  118  is provided with a central opening  142 . A tubular member  144  extends between the cap opening  142  and the discharging opening  132  of the reservoir  114 . The tubular member  144  establishes a flow path for the soap  126  from the reservoir  114  to the cap opening  142 . The cap opening  142  constitutes a dispensing opening through which the soap  126  is dispensed from the soap dispenser  110 . As in the embodiment of FIG. 1, the tubular member  144  is designed to inhibit or prevent the dripping of soap from the dispenser  110 . To this end, it is preferred for the tubular member  144  to have a generally S-shaped configuration as shown. Thus, the tubular member  144  includes a straight section  144   a  extending from the dispensing opening  142 , a straight section  144   b  extending from the discharging opening  132 , and a curved section  144   c  connecting the straight sections  144   a , 144   b  to one another. The curved section  144   c  defines a depression between the straight sections  144   a , 144   b.    
     Also mounted in the cap  118  are an energy emitter  148  and an energy detector  150 . The energy emitter  148  is arranged to direct energy to a location which faces the dispensing opening  142  in the cap  118  and is spaced from the cap  118 . On the other hand, the energy detector  150  is arranged to detect energy reflected from an object at such location. The energy detector  150  is designed to detect energy having the same frequency or frequency range as the energy emitted by the energy emitter  148 . 
     The cap  118 , or at least the portions of the cap  118  adjacent to the energy emitter  148  and the energy detector  150 , are transparent to the energy emitted by the energy emitter  148 . Hence, the cap  118  does not interfere with the transmission of energy emitted by the energy emitter  148 . The energy emitter  148  and the energy detector  150  are preferably designed to emit and detect infrared radiation. The energy emitter  148  and the energy detector  150  are spaced from one another, and a partition or wall  152  extends across the interior of the cap  118  between the energy emitter  148  and the energy detector  150 . The partition  152  separates the energy emitter  148  and the energy detector  150  from each other and is opaque to the energy emitted by the energy emitter  148 . The partition  152  prevents energy generated by the energy emitter  148  from reaching the energy detector  150  unless the energy has been reflected from an object which faces the dispensing opening  142  and is spaced from the cap  118 . Thus, the partition  152  prevents energy generated by the energy emitter  148  from traveling directly to the detector  150 . Likewise, the partition  152  prevents energy which is generated by the energy emitter  148  and then reflected by the cap  118  from reaching the energy detector  150 . 
     With reference to FIG. 5, the energy emitter  148  is driven by an oscillator  154  which functions as a clock. Thus, the oscillator  154  periodically sends a signal to the energy emitter  148  which thereupon generates an energy pulse having a predetermined frequency. The signals produced by the oscillator  154  also go to a coincidence and frequency discrimination unit  156 . The energy detector  150  is energized whenever the energy detector  150  senses energy having a frequency within a predetermined range. The energy detector  150  then generates output signals indicative of the frequency of the energy impinging upon the energy detector  150 . The signals produced by the energy detector  150  are sent to the discrimination unit  156 . 
     The discrimination unit  156  performs two main functions. On the one hand, the discrimination unit  156  determines whether the signals arriving from the energy detector  150  coincide with the signals arriving from the oscillator  154 . On the other hand, the discrimination unit  156  determines whether the energy sensed by the energy detector  150  has the same frequency as the energy emitted by the energy emitter  148 . If both conditions hold true, the discrimination unit  156  concludes that the energy detector  150  is sensing energy coming from the energy emitter  148  by reflection from an object near the dispensing opening  142 . The discrimination unit  156  then causes the valve  140  to assume its open condition. When the signals from the energy detector  150  cease, no longer coincide with the signals from the oscillator  154 , or no longer have the same frequency as the signals from the energy emitter  148 , the discrimination unit  156  causes the valve  140  to assume its closed condition. The oscillator  154  can be keyed to the discrimination unit  156 . 
     Referring back to FIG. 4, the valve  140 , energy emitter  148 , energy detector  150 , oscillator  154  and discrimination unit  156  are all fixed to a circuit board  158  removably mounted inside the cap  118 . The circuit board  158  runs circumferentially of the cap  118  and may be circumferentially complete. If the circuit board  158  is circumferentially complete, the circuit board  158  is provided with a central opening for the tubular member  144 . The circuit board  158  can, for example, have a generally annular configuration. Power for the valve  140 , energy emitter  148 , energy detector  150 , oscillator  154  and discrimination unit  156  is supplied by a small battery connected to the circuit board  158 . 
     The soap dispenser  110  is of the gravity-fed type as opposed to the pump type. Thus, with the soap dispenser  110 , gravity rather than a pumping action is used to discharge the soap  126  from the dispenser  110 . 
     One manner of operation of the dispenser  110  will be described assuming that the dispenser  110  is mounted on a wall in the upright position of FIG.  2 . It is further assumed that the energy emitter  148  emits infrared radiation and that the energy detector  150  is designed to sense infrared radiation. The energy emitter  148  periodically emits a pulse of infrared radiation having a predetermined frequency. The rate at which the pulses are generated is determined by the oscillator  154  which activates the energy emitter  148  at regular intervals and sends a signal to the discrimination unit  156  upon each activation. As long as no objects are placed below and in the vicinity of the dispensing opening  142 , the radiation pulses are dissipated and are not detected by the energy detector  150 . Consequently, the energy detector  150  sends no signals to the discrimination unit  156  which, in turn, causes the valve  140  to be in its closed condition. The space  128  above the soap  126  in the soap container  112  is cut off from the atmosphere and a vacuum exists in the space  128 . The vacuum prevents the soap  126  from flowing out of the reservoir  114 . 
     When a hand is placed below and within a predetermined distance of the dispensing opening  142 , the infrared radiation from the energy emitter  148  is at least partially reflected by the hand to the energy detector  150 . Upon sensing the reflected radiation, the energy detector  150  generates signals which are sent to the discrimination unit  156 . These signals are indicative of the frequency of the infrared radiation sensed by the energy detector  150 , and the discrimination unit  156  determines whether such frequency is the same as the frequency of the infrared radiation emitted by the energy emitter  148 . Furthermore, the discrimination unit  156  determines whether the signals generated by the oscillator  154  and the signals generated by the energy detector  150  arrive at the discrimination unit  156  at the same intervals. If the frequency of the infrared radiation detected by the energy detector  150  equals the frequency of the infrared radiation emitted by the energy emitter  148  and the signals from the oscillator  154  and the energy detector  150  are received at the same intervals, the discrimination unit  156  causes the valve  140  to assume its open condition. The space  128  above the soap  126  is then placed in communication with the atmosphere and the pressure in the space  128  increases to atmospheric pressure. The soap  126  can thereupon flow out of the reservoir  114  into the tubular member  144  and through the dispensing opening  142  onto the hand below the opening  142 . 
     Upon withdrawal of the hand from below the dispensing opening  142 , infrared radiation from the energy emitter  148  is no longer reflected to the energy detector  150 . The energy detector  150  stops sending signals to the discrimination unit  156  which, in turn, causes the valve  140  to return to its closed condition. When the valve  140  closes, the space  128  above the soap  126  is again cut off from the atmosphere and a vacuum redevelops in the space  128 . Since the vacuum must overcome the kinetic energy of the flowing soap  126 , the vacuum overshoots the value required to simply prevent the outflow of the soap  126  from the reservoir  114  when the soap  126  is stationary. As a result, once the soap  126  stops flowing, the relatively small volume of soap  126  present in the straight section  144   a  of the tubular member  144  is drawn into the curved section  144   c  of the tubular member  144 . Inasmuch as the curved section  144   c  defines a depression between the straight sections  144   a , 144   b  of the tubular member  144 , the soap  126  drawn out of the straight section  144   a  and into the curved section  144   c  is unable to escape from the curved section  144   c  while the valve  140  remains closed. Consequently, dripping of the soap  126  from the dispensing opening  142  is prevented. 
     The energy emitter  148  and the energy detector  150  of the soap dispenser  110  make it possible for the soap  126  to be discharged without touching the dispenser  110 . Hence, the dispenser  110  is more sanitary than conventional soap dispensers. The removable cover  116  of the soap container  112  also allows easy access to the interior of the reservoir  114  so that the reservoir  114  can be easily cleaned. 
     Inasmuch as the soap dispenser  110  employs gravity to discharge the soap  126  from the dispenser  110 , the dispenser  110  is relatively efficient. The efficiency of the dispenser  110  is enhanced because the fluid directly controlled by the valve  140  is air rather than the relatively viscous soap  126 . 
     Since the valve  140  need only allow the passage of air therethrough, the valve  140  can be designed with a small flow aperture. This enables the valve  140  to be actuated with a relatively small amount of energy as the energy required to actuate a valve increases with increasing flow aperture size. Consequently, the energy supplied by a single small battery can suffice to operate the dispenser  110  for an extended period, e.g., 90 days. Moreover, the same valve can be used to dispense liquids with a wide range of viscosities. 
     Various modifications are possible within the meaning and range of equivalence of the appended claims. For example, the liquid dispensed could equivalently be, without limitation, a soap, a lotion, a beverage, a cleaner, a disinfectant, an adhesive, or a fabric treatment. Similarly, the container could consist of a deformable structure. Therefore, while the invention has been shown and described herein in what is believed to be the most practical and preferred embodiments, it is recognized that departures can be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent processes and products.