Abstract:
A litter box monitoring system including: one or more sensors associated with one or more litter boxes; one or more processors; and one or more non-transitory computer readable media coupled to the one or more processors having instructions stored thereon which, when executed by the one or more processors, cause the one or more processors to perform a method comprising: detecting, using the one or more sensors, at least one of entry or exit of an animal relative to the one or more litter boxes; and calculating, using the one or more processors, frequency of use of the one or more litter boxes based on the detected at least one of entry or exit of an animal relative to the one or more litter boxes.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/117,512, filed May 27, 2011, which is a non-provisional application based on U.S. Provisional Patent Application 61/348,803, filed May 27, 2010, and U.S. Provisional Patent Application 61/433,019, filed Jan. 14, 2011, the contents all of which are incorporated herein by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to a cat litter box including an automated litter tray cleaning cycle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    The features and advantages of the disclosure will be more fully understood with reference to the following description of the invention when taken in conjunction with the accompanying figures, wherein: 
           [0004]      FIGS. 1A-1F  illustratively depict a cat litter box system capable of substantially emptying the contents of the litter tray in accordance with exemplary embodiments of the disclosure; 
           [0005]      FIG. 2  illustratively depicts various elements of a cat litter box system in accordance with exemplary embodiments of the disclosure; 
           [0006]      FIG. 3  illustratively depicts a user interface in accordance with exemplary embodiments of the disclosure; 
           [0007]      FIG. 4  illustratively depicts a network of cat litter boxes according to an exemplary embodiment of the present invention; 
           [0008]      FIG. 5  illustratively depicts the operation of a network of cat litter boxes according to an exemplary embodiment of the present invention; 
           [0009]      FIG. 6  is a partially cut-away perspective view of a cat litter box according to an exemplary embodiment of the present invention; 
           [0010]      FIG. 7  is a perspective view showing a cat litter tray drive system and a base frame according to an exemplary embodiment of the present invention; 
           [0011]      FIG. 8  is a partial perspective view of a cat litter box according to an exemplary embodiment of the present invention; 
           [0012]      FIG. 9  is a perspective view showing a cat litter tray and a cat litter drive system according to an exemplary embodiment of the present invention; 
           [0013]      FIG. 10  is a perspective view showing a return bin and a return bin drive system according to an exemplary embodiment of the present invention; 
           [0014]      FIG. 11-14  are plan views showing the pivotal movement of a filter as the return bin is driven upwards by a return bin drive system according to an exemplary embodiment of the present invention; 
           [0015]      FIGS. 15-18  are cross-sectional view of a hopper as it fills a return bin with cat litter according to an exemplary embodiment of the present invention; 
           [0016]      FIG. 18  is a perspective view showing a hopper in a fully opened position as it fills a return bin with cat litter according to an exemplary embodiment of the present invention; 
           [0017]      FIGS. 19 and 20  are perspective view of a cat litter return bin and cat litter return bin drive system according to an exemplary embodiment of the present invention; 
           [0018]      FIG. 21  is a perspective view of a return bin transport drive mechanism according to an exemplary embodiment of the present invention; 
           [0019]      FIG. 22  is a front cross sectional view of a cat litter box showing a return bin on top of the tray according to an exemplary embodiment of the present invention; 
           [0020]      FIGS. 23-25  are perspective views showing the operation of a return bin as it is driven over cat litter tray according to an exemplary embodiment of the present invention; 
           [0021]      FIG. 26  is a partially cut away perspective view of a cat litter box according to an exemplary embodiment of the present invention; 
           [0022]      FIG. 27  is a perspective view of a cover drive system according to an exemplary embodiment of the present invention; and 
           [0023]      FIG. 28  is a partially cut away perspective view of a cat litter box according to an exemplary embodiment of the present invention. 
       
    
    
     SUMMARY OF THE INVENTION 
       [0024]    A litter box monitoring system according to an exemplary embodiment of the present invention comprises: one or more sensors associated with one or more litter boxes; one or more processors; and one or more non-transitory computer readable media coupled to the one or more processors having instructions stored thereon which, when executed by the one or more processors, cause the one or more processors to perform a method comprising: detecting, using the one or more sensors, at least one of entry or exit of an animal relative to the one or more litter boxes; and calculating, using the one or more processors, frequency of use of the one or more litter boxes based on the detected at least one of entry or exit of an animal relative to the one or more litter boxes. 
         [0025]    In at least one embodiment, the method further comprises the steps of: comparing, using the one or more processors, the calculated frequency to a predetermined frequency parameter; and generating, using the one or more processors, an alert upon the condition that the calculated frequency is outside the predetermined frequency parameter. 
         [0026]    In at least one embodiment, the method further comprises the step of: determining, using the one or more processors, an identity of an animal using the one or more litter boxes. 
         [0027]    In at least one embodiment, the step of determining is based on data read by the one or more sensors from an RFID tag. 
         [0028]    In at least one embodiment, the method further comprises the step of monitoring, using the one or more processors, behavior of the identified animal based on the calculated frequency of use. 
         [0029]    In at least one embodiment, the method further comprises the step of detecting, using the one or more sensors, weight of the identified animal. 
         [0030]    In at least one embodiment, the step of determining an identity of the animal is based on the detected weight of the animal. 
         [0031]    In at least one embodiment, the method further comprises the step of calculating, using the one or more processors, weight change of the identified animal based on the detected weight. 
         [0032]    In at least one embodiment, the method further comprises the steps of: comparing, using the one or more processors, the calculated weight change to a predetermined weight change parameter; and generating, using the one or more processors, an alert upon the condition that the calculated weight change is outside the predetermined weight change parameter. 
         [0033]    In at least one embodiment, the method further comprises the steps of: detecting, using the one or more processors, that a first litter box of the one or more litter boxes is being used by an animal; and controlling, using the one or more processors, operation of a second litter box of the one or more litter boxes so that the second litter box does not operate while the first litter box is operating. 
         [0034]    In at least one embodiment, the step of controlling comprises delaying operation of the second litter box for a predetermined period of time. 
         [0035]    In at least one embodiment, the step of controlling comprises terminating operation of the second litter box. 
         [0036]    In at least one embodiment, each of the one or more litter boxes comprises a respective one of the one or more sensors, a respective one of the one or more processors and a respective one of the one or more computer readable media. 
         [0037]    In at least one embodiment, each of the one or more litter boxes comprises a respective one of the one or more sensors, and the one or more processors and the one or more computer readable media are part of a central computer system. 
         [0038]    An automated cat litter box according to an exemplary embodiment of the present invention comprises: a cat litter tray; a cat litter return bin that collects soiled cat litter from the cat litter tray and that returns recycled cat litter to the cat litter tray; a control unit; and one or more drive units operated by the control unit to drive the cat litter tray and the cat litter return tray to automatically recycle the soiled cat litter during a cat litter box cleaning cycle. 
         [0039]    In an exemplary embodiment, the one or more drive units automatically pivot the cat litter tray between a first configuration in which the cat litter tray may be used to collect cat waste and a second configuration in which the cat litter tray may be emptied into the cat litter return bin. 
         [0040]    In an exemplary embodiment, the automated cat litter box further comprises a hopper, and the one or more drive units move the cat litter return bin between a first configuration in which the cat litter return bin is in position to collect soiled cat litter from the cat litter tray, a second configuration in which the cat litter return bin is in position to collect fresh cat litter from the hopper, and one or more third configurations in which the cat litter return bin is disposed over the cat litter tray to deliver the recycled cat litter to the cat litter tray. 
         [0041]    In an exemplary embodiment, the automated cat litter box further comprises: a filter; and a waste bin, wherein the filter is disposed within the cat litter return bin when the cat litter return bin is in the first configuration, and the filter is disposed out of the cat litter return bin and in position to dispose of filtered waste to the waste bin when the cat litter return bin is in the second configuration. 
         [0042]    In an exemplary embodiment, the waste bin comprises a waste bin cover, and the waste bin cover is substantially closed when the cat litter return bin is in the first configuration and the waste bin cover is substantially open when the cat litter return bin is in the second configuration. 
         [0043]    In an exemplary embodiment, the automated cat litter box further comprises one or more pivot arms that attach the waste bin cover to the cat litter filter. 
         [0044]    In an exemplary embodiment, the one or more drive units comprise one or more of the following types of drives: screw drives and chain drives. 
         [0045]    In an exemplary embodiment, the cat litter return bin comprises one or more wheels that allow the cat litter return bin to move to the one or more third configurations. 
         [0046]    In an exemplary embodiment, the cat litter tray comprises a raised rim that contacts the wheels so that the cat litter return bin is guided over the cat litter return bin when moving to the one or more third configurations. 
         [0047]    In an exemplary embodiment, the cat litter return bin comprises a bottom wall that is pivotal between one or more open configurations and a closed configuration, and the bottom wall is in the closed configuration when the cat litter return bin is in the first and second configurations, and the bottom wall is in the one or more open configurations when the cat liter return bin is in the one or more third configurations. 
         [0048]    In an exemplary embodiment, the bottom wall comprises fins that evenly spread the recycled cat litter over the cat litter tray. 
         [0049]    In an exemplary embodiment, at least one of the one or more drive units comprises a motor. 
         [0050]    In an exemplary embodiment, one of the one or more drive units comprises a guide rail and wheels that travel within the guide rail, and the one of the one or more drive units drives the cat litter tray. 
         [0051]    In an exemplary embodiment, the automated cat litter box further comprises a monitoring system that detects a cat&#39;s behavior relative to the cat litter box. 
         [0052]    In an exemplary embodiment, the automated cat litter box further comprises a base frame that supports at least one of the cat litter tray, the cat litter return bin and the one or more drive units. 
         [0053]    In an exemplary embodiment, the automated cat litter box further comprises a cover that covers at least the cat litter return bin. 
         [0054]    In an exemplary embodiment, the cover comprises a front cover component and a back cover component, the front cover component being moveable relative to the back cover component between a first configuration in which the cat litter tray is covered by the front cover component and a second configuration in which a substantial portion of the cat litter tray is not covered by the front cover component. 
         [0055]    In an exemplary embodiment, the one or more drive units automatically move the front cover component between the first and second configurations. 
         [0056]    In an exemplary embodiment, the cover comprises a door, and the one or more drive units automatically move the door to seal the cat litter box during the cleaning cycle. 
         [0057]    In an exemplary embodiment, the control system comprises one or more computers that perform one or more of the following functions: network with other cat litter box computers, collect and send data to one or more other computers, and receive control signals from one or more other computers. 
       DETAILED DESCRIPTION 
       [0058]    Referring to  FIGS. 1A-1F , the cat litter box system can be configured to include a litter tray cleaning cycle such that, after use by a cat, the contents of the litter tray are substantially emptied into a filter separating out the clean litter from the dirty litter. After being substantially emptied and filtered, the litter box is refilled by the filtered clean litter and, if needed, additionally filled by a hopper. 
         [0059]    As shown in  FIG. 1A , initially, cat litter box  100  including litter tray  102  is filled with a quantity of litter. After an animal uses litter tray  102  (e.g., urinates and/or defecates) a sensor (not shown) capable of detecting the animal&#39;s entrance and/or exit detects the animals presence and begins the litter tray cleaning cycle. This sensor may be a weight sensor. In some instances, a timer (not shown) can be used to delay the start of the litter tray cleaning cycle. 
         [0060]    Referring to  FIG. 1B , litter tray  102  can be substantially emptied using an electro-mechanical process. For example, litter tray  102  can be emptied by tilting up on one side of litter tray  102  by a lift mechanism  104  and allowing substantially the entirety of litter to be poured out of litter tray  102 . The poured litter then flows through a litter filter  106 . Litter filter  106  may have more than one layer, allowing it to filter large, medium, and small clumps of soiled litter. Litter filter  106  may also be designed to channel litter flow for a more even distribution as the litter moves through litter filter  106 . Litter filter may also be designed so that the filter membrane is easily removable and replaceable. 
         [0061]    Referring to  FIG. 1C , the filtered waste items  108  can then be ejected from litter filter  106  into a waste bin  110 . Waste bin  110  can hold a quantity of waste and can be easily removed. The filtered unclumped or “clean” litter that is separated from the waste items  108  can be caught in a litter return bin  112 . 
         [0062]    Referring to  FIG. 1D-1E , litter return bin  112  can move relative to litter tray  102  and can replenish litter tray  102 . For example, the litter return bin  112  can be transported up and over litter tray  102 , releasing and spreading the clean litter back into empty litter tray  108 . Then, referring to  FIG. 1F , litter return bin  112  returns to its starting position. 
         [0063]    Referring back to  FIG. 1D , in some instances, prior to releasing the clean litter, litter return bin  112  can be filled. For example, prior to releasing the clean litter, litter return bin  112  may stop at a “refill” point at a new litter hopper  114 . New litter hopper  114  can, for example, hold either loose litter that can be added by a user, or it can accommodate a separate litter bottle through a connection. New litter hopper  114  can also have a “reservoir” area, so that the unit can still function with an empty (or not [un]connected litter bottle). This may also assist in changing connected litter bottles. 
         [0064]    New litter hopper  114  can also have a release mechanism that allows new litter to be added to litter return bin  112 , as the volume of litter in litter tray  102  is depleted through clumping and disposal. This can allow for the specified quantity of litter to be maintained in litter tray  102  at all times. It may also reduce the user&#39;s involvement in refilling litter. 
         [0065]    A computer  116  in communication with another computer and/or a computer network, and associated computer software can be used. For example, data can be collected and transmitted through one or more wired or wireless computer networks. Software used on a computer can interpret the data and take actions as defined by the software. Actions might include sending a message to the user through an email service, outside website, or Bluetooth device, etc. Such software may be implemented as computer-readable code that, when read by a computer processor, causes the cat litter box  100  to perform one or more operations, such as, for example, a cleaning cycle that involves a number of operations performed in a specific sequence with specific timing parameters. 
         [0066]    For example, referring to  FIG. 3 , applications of data collected and transmitted can include, but is not limited to, operation of components, such as cycle times, electrical measurements, etc.; user alerts to refill the new litter hopper  114 , empty the waste bin, respond to error messages, etc.; monitor the placement/removal of new litter bottles that can allow for an “auto-reorder” process, so that the user has an adequate supply of litter on-hand at all times. In exemplary embodiments, it should be appreciated that the cat litter box  100  may include any combination of software and/or hardware components that allow for full or partial automation of the cat litter box  100 . One or more of the software and/or hardware components may be disposed within the cat litter box  100 , while other software and/or hardware components may be disposed external to the cat litter box  100 . 
         [0067]    Specialized litter bottles pre-filled with litter may be provided as a service in conjunction with cat litter box system  100 . 
         [0068]    Further, cat litter box  100  can include an identification system, such as a radio-frequency identification (RFID) system, in order to track individual cat activity. As part of a monitoring system, data with important health implications, such as average trips to cat litter box system  100  per a set period of time can be stored and transmitted. User alerts can be sent if there is a significant change in behavior, such as no visits to cat litter box system  100  in 24 hours. Parameters for determining whether to send an alert can be user-definable. 
         [0069]    The monitoring system may include a weight sensor in litter tray  102 , so that the cat litter box system  100  can store and transmit historical weight information on the cat(s) that use it. For example, user alerts can be sent if a weight change violates a range, where the range may be user definable. Use of a weight sensor may also allow for the identification of individual cats using litter box system  100 . Use of a weight sensor may also allow for the determination of the type and quantity of waste left by a cat in litter box system  100 , including the storage, retrieval, and transmission of such data. 
         [0070]    As shown in  FIG. 4 , a number of cat litter boxes  100 , each including a computer  116 , can be in communication with one another through a central network  300 . The network  300  may be particularly useful when the cat litter boxes  100  are used in the same central location, such as, for example, at a house, breeder, veterinary clinic, etc. A central server  310  operably connected to a central computer system  320  of the network  300  may collect data from each of the computers  116  and may send instructions to each of the computers  116  regarding, for example, operation of components, such as cycle times, electrical measurements, etc.; user alerts to refill the new litter bin  114 , empty the waste bin, respond to error messages, etc.; monitor the placement/removal of new litter bottles that can allow for an “auto-reorder” process, so that the user has an adequate supply of litter on-hand at all times. In an exemplary embodiment, the network computer system  320  may be used to set the time period for initiating a cleaning-cycle for each of the cat litter boxes  100  in the network. For example, a cleaning cycle for each of the cat litter boxes  100  within the network may be set to begin after a predetermined waiting period, such as, for example, a waiting period of 10 minutes, after an animal has used the cat litter box  100 . It should be appreciated that the network  300  need not include a central computer, and instead the computers  116  of each cat litter box  100  may be in communication with one another to form the network  300  without a central computer. The cat litter boxes  100  within the network  300  may be in communication with one another via wired or wireless connections, such as, for example, Wi-Fi, Bluetooth, Ethernet, etc. 
         [0071]    A problem that may arise within the network  300  of cat litter boxes  100  is that a first box&#39;s cleaning cycle may commence while a second animal is using a second box within the network. The noise from the first box&#39;s operation may scare the second animal, causing it to flee before it has “finished,” creating a mess, and also providing negative feedback to that animal about using that litter box. In order to avoid this problem, the cleaning cycle may be set such that, when an animal enters one box on the network and triggers the on-board sensor in that box, all of the other boxes on the network will receive an electronic command to “reset” any pending cleaning-cycle countdown timers to a minimum waiting period, such as, for example, a minimum waiting period of two minutes. 
         [0072]      FIG. 5  illustrates the operation of the network  300  according to an exemplary embodiment of the present invention. In this example, the cycle timer is set to 8 minutes. Initially, Box A and Box B are vacant, and therefore no timers are running. At network time 12:01, an animal may enter Box A, which triggers a sensor within Box A and the cleaning-cycle timer begins counting down from 8 minutes. At network time 12:08, Box A is now vacant, and the cleaning-cycle timer will expire in 1 minute. At this time, a second animal enters Box B, thereby triggering the sensor in Box B. A message may be sent from Box B to Box A via the network  300  to reset the timer in Box A for an additional 2 minutes. This will give the animal in Box B enough time to complete use of Box B without being frightened by a cleaning cycle operation commencing nearby in Box A. At network time 12:11, both Box A and Box B are vacant, the Box A timer has expired and the cleaning cycle in Box A has been initiated, and the Box B timer has 5 minutes remaining. 
         [0073]    Referring to  FIG. 2 , cat litter box system  100  can also include an air filtration system  202 , allowing air to be drawn from the outside, down through the base of cat litter box system  100 , helping to minimize dust and odors. Further, the cat litter box system  100  can include a cover  204 . The cover can have an opening for the animal&#39;s entrance and exit. The cover may be retractable, and may move back and forth over the litter tray, so that the system can be operated as an uncovered system or a covered one. The cover may be moved mechanically so that the system can be used by an animal in an uncovered configuration, and then automatically cover the litter area at the onset of the cleaning cycle. This will reduce dust and odors. 
         [0074]    A retractable door may be used, so that the unit&#39;s egress can be mechanically blocked and unblocked. When the door is fully refracted, an animal may enter the litter area. Upon activation of the cleaning cycle, the door may automatically move forward until it finally forms a seal around the egress, thereby helping reduce dust and odors and preventing an animal from entering the system during a cleaning cycle. 
         [0075]    The retractable cover and the retractable door may be attached to one another such that one mechanically operated component (the door, for example) can “push” and “pull” the other component (the cover, in this example) back and forth from a fully expanded position to a fully retracted position. 
         [0076]    There can also be a retractable litter catch pad  206  that may, for example, extend from a base  208  under the door in cover  204 . This may assist in the retention of scattered or tracked litter. 
         [0077]    Cat litter box system  100  can further include a maintenance cycle. This maintenance cycle may empty litter tray  102  and lower litter tray  102  back into position after the waste has been expelled from the litter filter  106 . At this point, a user can remove litter tray  102 , waste bin  110 , litter return bin  112 , litter filter  106 , etc. for cleaning and/or replacement. The entire quantity of used litter in the litter return bin  112  can be easily discarded. 
         [0078]    Waste bin  110  can be designed to accommodate disposable bags, which may be odor-reducing. 
         [0079]    Further, litter tray  102  can have sides that are inwardly curved at the top to help deflect scattered litter back into the box. 
         [0080]    Cover  204  can be a full cover so the entire box is enclosed and may include an entrance door on one side. Further, cover  204  can be designed for simple placement and removal. 
         [0081]    Further cat litter box  100  can include a track  212  that can be used by litter return bin  112  to move and distribute filtered litter. 
         [0082]    Litter tray  102  can be a box with curved/angled sides to help redirect scattered litter back into the box. Litter tray  102  can be designed for optimal pouring into litter filter  106  and can be constructed of and/or coated with a non-stick material. Further cat litter box  100  can include a potential humidity mitigation system (not shown). Litter tray  102  can be designed for simple placement and removal. Litter tray  102  can rest on a tilting mechanism, so that box can be tilted to dump litter. Litter tray  102  may also be fitted with a weight sensor, in order to track cat activity. 
         [0083]    Computer  116  can be capable of communicating to another computer via a network and/or wirelessly. Computer  116  can allow for the collection and transmission of relevant data and alerts regarding the operation of cat litter box system  100  and the cat(s) using it. Specific data can include, but is not limited to, component cycle times, electrical measurements, and other measures that reveal the operational characteristics of cat litter box system  100 . User alerts can include those to refill the new litter hopper  114 , empty waste bin  110 , as well as error messages. 
         [0084]    Further cat litter box  100  can also monitor the placement/removal of new litter bottles, allowing an “auto-reorder” process to provide an adequate supply of litter at all times. Specialized litter bottles pre-filled with litter may be provided as a service in conjunction with cat litter box system  100 . 
         [0085]    Further, cat litter box  100  can include and/or work with a weight sensor, an RFID tag and antenna system or another means to track individual cat activity. Health data can be generated as an alert to potential underlying health problems, such as kidney disease or diabetes. This may be especially helpful because as cats age, too much or too little urination can be a key early indicator of otherwise asymptomatic disease. In addition, a litter tray weight sensor allows cat litter box system  100  to monitor and provide historical weight information, also potentially important to detect changes in a cat&#39;s health status in between veterinary exams. Diseases such as hyperthyroidism are common in cats, and weight change is often the earliest indicator of underlying disease. Detection of disease-related weight changes may be the earliest indicators of underlying disease in an otherwise asymptomatic cat. Cat litter box  100  can alert the user if a cat does not use the box for an extended period of time. This can be especially important when the user will be away from the litter box for an extended period of time, during which time a cat is potentially isolated away from the litter box (locked in a separate area of a home, for example), sick and/or injured, etc. 
         [0086]    New litter hopper  114  may allow for placement of new litter, either poured into the hopper or through a direct connection between the hopper and another litter container. New litter hopper  114  can be designed to have a reservoir system, allowing for replacement of a litter bottle before it is completely empty. New litter hopper  114  can be designed to add new litter to the litter return bin each time the litter return bin cycles through the system. If the litter return bin contains too little litter, new litter will be added from the hopper, ensuring a desired amount of litter is dispensed by the clean litter hopper into the litter tray  102  at all times. 
         [0087]    Air filter  202  can provide a mechanism for air to be drawn from cat litter box system  100  through filter  202 , preventing dust and odors from escaping. Air filter  202  can cycle on and off when cat litter box system  100  is in use. 
         [0088]    Litter filter  106  can include a double or multi-layered screening device to separate large, medium, and small bits of clumped litter, while allowing clean litter to flow through and into the litter return bin. Litter filter  106  can be connected to a mechanism that swings litter filter  106  back and forth, into and out of the waste bin. As litter filter  106  is swung into waste bin  110 , and against a stop, the force and downward angle can propel the waste into waste bin  110 , in a back-to-front, bottom-to-top pattern, that can substantially increase waste storage capacity. Litter filter  106  may be made of or coated with a non-stick material. Litter filter  106  may be designed to be easily removable for cleaning, and/or replacement. Litter filter may be designed to swing back and forth using a passive mechanical system that is connected to another mechanical system. 
         [0089]    Litter catch pad  206  can be pulled out of the base  208 , allowing for an area for the catchment of scattered or tracked litter outside litter tray  102 . Further, litter catch pad  206  can be adjusted by the user to accommodate usable floor space. Base  208  may incorporate a step up to the door (not shown) and can have a retractable litter catch pad  206 . 
         [0090]    Further cat litter box  100  can include a Frame  214 . Frame  214  can be designed to hold litter tray  102  and may or may not be connected to lift mechanism  104 . 
         [0091]    Waste bin  110  can be designed to hold, for example, up to one month of waste from a single cat. Waste bin  110  can also include sealed mouth to contain odors. Waste bin door can be designed to open and close using a passive mechanical system that is driven by another mechanical system. Waste bin  110  can hold odor-reducing waste bags and waster bin  110  can be installed and removed with substantial ease. 
         [0092]    Lift mechanism  104  can be designed to raise and lower litter tray for dumping of soiled litter. 
         [0093]    Litter return bin  112  can catch clean litter poured through litter filter  106 , and transport and distribute it back to litter tray  102 . Litter return bin  112  can be lifted on an elevator platform, and then connect to a forward and reverse transport mechanism. When pulled forward off the elevator platform, the litter return bin  112  can have a door on its underside that will open and hang down, through which the clean litter can flow back into litter tray  102 . The door can be designed to hang at a height that will spread the poured litter at the proper level. The door can also have “fins” to help control the distribution of litter in the tray. 
         [0094]    In an exemplary embodiment, the cat litter box  100  may include a programmable 24-hour, 7-day system control timer. Such a timer may allows a user to schedule operable and inoperable periods for system cleaning cycle, as well as customizable cleaning cycle delay settings. For example, the user may set the system timer for a 30-minute cleaning cycle delay between the hours of 0800 and 1800, Monday through Friday, while the user is away at work and odor is not an issue and he wants waste to fully harden before being filtered. The user may set the timer for a 10-minute delay from 1800 to 2300 Monday through Friday, when he is at home and odor is more of a concern than fully hardened waste. The user may set the timer not to operate between the hours of 2300 and 0600, when he is asleep and does not want to be disturbed by the sound of the system running 
         [0095]      FIG. 6  is a partially cut-away perspective view of a cat litter box, generally designated by reference number  500 , according to an exemplary embodiment of the present invention. The cat litter box  500  includes a cover  510 , a base frame  520 , a cat litter tray  530 , a cat litter tray drive system  540 , a cat litter return bin  550 , a cat litter return bin drive system  560  (shown in  FIG. 10 ), a cat litter filter  570 , a waste bin  580 , a hopper  590 , and a cat litter return bin transport drive system  600 . Each of these components will be described below with reference to  FIGS. 6-8 , which also show the operation of the cat litter box  500  during a litter tray cleaning cycle. Although the present description refers to separate drive systems for the cat litter tray and the cat litter return bin, it should be appreciated that one or more drive systems may be used to operate the one or more various components of the cat litter box. 
         [0096]      FIG. 7  is a perspective view showing the cat litter tray drive system  540  and the base frame  520  according to an exemplary embodiment of the present invention. The base frame  520  may include a number of frame elements  522  that support the various components of the cat litter box  500 , including the components of the tray drive system  540 . In this regard, the base frame  520  may include guide rails  524  that guide the movement of the tray drive system  540 . In particular, as described in further detail below, the tray drive system  540  may include wheels  541  that are driven back and forth within the guide rails  524  so as to raise the cat litter tray  530  into a dumping position over the return bin  550  and lower the cat litter tray  530  back to its use position. As shown in  FIG. 8 , the wheels  541  may include a number of spherical ridges  542  around the outer circumference of the wheels  541  that protrude into corresponding openings  548  within the guide rails  524 . The spherical ridges  542  and guide rail openings  548  allow the guide rails  524  to remain free of cat litter that may otherwise get trapped within the guide rails  524  and interfere with movement of the wheels  541 . It should be appreciated that in other exemplary embodiments of the invention, the ridges  542  may have a shape other than spherical, such as, for example, rectangular or triangular. 
         [0097]    The tray drive system  540  may include a motor  543  that drives a screw shaft  544 . An internally threaded collar  545  translates the rotation of the screw shaft  544  by the motor  543  to straight-line motion of the wheels  541  within the guide rails  524 . In this regard, the tray drive system  540  may include a tray drive system frame  546  that connects the collar  545  to the wheels  541 . The tray drive system frame  546  may also include upwardly extending arms  547 , the distal ends of which are pivotally connected to sides of the cat litter tray  530 . As shown in  FIG. 9 , movement of the wheels  541  back towards the cat litter return bin  550  causes the tray  530  to pivot around its front end towards a dumping position. In this regard, the back end of the tray  530  may be hinged to the upper portion of a first support frame  526  that extends upward from the base frame  520 . The tray  530  may be hinged to the first support frame  526  by any suitable hinging mechanism, such as, for example, a living hinge or a barrel hinge. 
         [0098]    Once the contents of the tray  530  are dumped into the return bin  550 , the return bin  550  is raised into position under the hopper  590  while the filter  570  is pivoted into a dumping position over the waste bin  580 . As described in detail below, the return bin  550  may be driven up and down by the return bin drive system  560 , which in turn causes the filter  570  to pivot into a dumping position and back into its original position within the return bin  550 . In this regard, as shown in  FIG. 6 , the back end of the filter  570  may be hinged to the upper portion of a second support frame  528  that extends upwards from the base frame  520 . The filter  570  may be hinged to the second support frame  528  by any suitable hinging mechanism, such as, for example, a living hinge or a barrel hinge. In an exemplary embodiment, the hinge is separable so that the filter  570  may be removed for cleaning or replacement by a new filter. 
         [0099]      FIG. 10  is a perspective view showing the return bin  550  and return bin drive system  560  according to an exemplary embodiment of the present invention. The return bin drive system  560  may include an elevator frame  561  that is raised and lowered by rotation of screw drives  562  that are connected to internally threaded collars  563  of the elevator frame  561 . The screw drives  562  may be driven by a chain drive including a motor  564 , drive chain  565  and sprocket gears  566 . The motor  564  drives the drive chain  565  to rotate the sprocket gears  566 , which in turn rotate the screw drives  562  that are connected to the sprocket gears  566 . The return bin  560  may rest on the elevator frame  561  so that the return bin  560  moves up and down with the driven elevator frame  561 . 
         [0100]      FIGS. 11-14  show the pivotal movement of the filter  570  as the return bin  550  is driven upwards by the return bin drive system  560  (for clarity, the return bin  550  is not shown in  FIGS. 11-14 ). The filter  570  is pivoted back into a dumping position as the elevator frame  561  moves upwards by operation of the return bin drive system  560 . The filter  570  may include lever arms  572 , the distal ends of which are connected to a waste bin door  582 . As the filter  570  pivots, lateral motion of the lever arms  572  cause the waste bin door  582  to pivot open so that the contents of the filter  570  may be dumped into the waste bin  580 .  FIG. 14  shows the elevator frame  561  in the completely raised position and the filter  570  pivoted back into the dumping position over the waste bin  580 . After sufficient time to allow the cat waste to be dumped from the filter  570  into the waste bin  580 , the elevator frame  561  may be lowered, which causes both the filter  570  to pivot back to its original position within the now lowered return bin  550  and the closure of the waste bin door  582 . 
         [0101]    Before being lowered, the return bin  550  may be refilled with cat litter from the hopper  590 .  FIGS. 15-18  show the operation of the hopper  590  as it fills the return bin  550  with cat litter according to an exemplary embodiment of the present invention. In particular,  FIGS. 15-17  are cross-sectional views of the hopper  590 , and  FIG. 18  is a perspective view of the hopper  590  when the hopper  590  is fully opened for delivery of cat litter to the return bin  550 . The hopper  590  may include a motor  591  and a nozzle mechanism  592  that is controlled by the motor  591  to deliver cat litter to the return bin  550 . The nozzle mechanism  592  may include a first nozzle portion  593  and a second nozzle portion  594 . In an exemplary embodiment, only the second nozzle portion  594  may form the bottom wall of the nozzle mechanism  592 . Operation of the motor  591  may cause the first and second nozzle portions  592 ,  593  to pivot relative to one another so that cat litter delivery slots  595  appear between the first and second nozzle portions  592 ,  593 . At the same time, the pivoting of the second nozzle portion  593  may expose a hopper opening  596 . The cat litter may then escape from the hopper opening  596  and fall onto the bottom wall of the nozzle mechanism  592  (formed by the second nozzle portion  594 ). The cat litter may then slide down the bottom wall of the nozzle mechanism  592  and escape from the delivery slots  595  into the return bin  550 . In an exemplary embodiment of the invention, the hopper  590  may operate in a passive mode in that cat litter is allowed to flow out of the hopper  590  until the level of the cat litter within the return bin  550  reaches the same level as that of the nozzle mechanism  592 , at which point no further cat litter can be released by the nozzle  592  into the return bin  550 . After a set period of time determined to be sufficient to allow for the complete refilling of the return bin by the hopper/nozzle assembly, operation of the motor  591  may cause the first and second nozzle portions  592 ,  593  to pivot relative to one another so that cat litter delivery slots  595  between the first and second nozzle portions  592 ,  593  may be closed so that no further cat litter can be released by nozzle mechanism  592 . At the same time, the pivoting of the second nozzle portion  593  may also close hopper opening  596  so that no further cat litter can be released by the hopper into the nozzle. It should be appreciated that any other control scheme, either passive or active, may be used to operate the hopper  590 . 
         [0102]    After being filled with cat litter by the hopper  590 , the return bin  550  may be automatically moved over the tray  530  by the return bin transport drive mechanism  600 . In this regard, as shown in  FIGS. 19 and 20 , the return bin  550  may include protrusions  551  that catch a corresponding bracket  601  of the return bin transport drive mechanism  600  as the return bin  550  is raised. The catching of the bracket  601  by the protrusions  551  allow the return bin  550  to be driven by the return bin transport drive mechanism  600  back and forth over the tray  530 . 
         [0103]      FIG. 21  is a perspective view of the return bin transport drive mechanism  600  according to an exemplary embodiment of the present invention. The return bin transport drive mechanism  600  may include motors  602  that cause rotation of corresponding screw drives  603  through drive trains  604 , such as, for example, sprocket gears and drive chains. Each of the brackets  601  may include a threaded collar  605  through which pass the screw drives  603  so that rotation of the screw drives  603  cause the brackets  601 , and hence the return bin  550  caught on the brackets  601 , to move back and forth over the tray  530  depending on the direction of rotation. Each bracket  601  may also include a secondary collar  606  that slides along a corresponding stability bar  607 . The stability bars  607  provide stability to the brackets  601  so that they remain in the required position to contact the return bin protrusions  551 , and also so that the brackets  601  are prevented from being rotated by the rotational movement of the screw drives  603 . 
         [0104]      FIG. 22  is a front cross sectional view of the cat litter box  500  showing the return bin  550  on top of the tray  530  according to an exemplary embodiment of the present invention. The return bin  550  may include wheels  552  that are exposed through corresponding openings in the bottom wall  555  of the return bin  550 . Each wheel  552  may include an inner flange  553  and an outer flange  554 . The tray  530  may include a raised rim  532  that protrudes through the openings in the bottom wall  555  of the return bin  550  to interface with the corresponding inner and outer flanges  553 ,  554  of the wheels  552 . In this regard, the rim  532  may have a cross sectional shape, such as, for example, triangular, that protrudes into the space between the inner and outer flanges  553 ,  554  of the wheels  552 . Thus, the rim  532  is able to act as a guide rail for the wheels  552  as the return bin  550  is driven over the tray  530 . The rim  532  and wheels  552  also provide additional stability to the return bin  550 . 
         [0105]      FIGS. 23-25  show the operation of the return bin  550  as it is driven over the tray  530  according to an exemplary embodiment of the present invention. The bottom wall  555  of the return bin  550  may be pivotally attached to the back wall  556  of the return bin  550 . Thus, when the return bin  550  is disposed on the elevator frame  561 , the bottom wall  555  is held closed. However, as the return bin  550  is driven over the tray  530 , the bottom wall  555  becomes free to pivot open, allowing the cat litter held within the return bin  550  to fall into the tray  530 . In this regard, the bottom wall  555  may include fins  557  which function to direct the flow of the cat litter evenly over the tray  530 . As shown in  FIGS. 24 and 25 , once fully opened, the bottom wall  555  may plow across the cat litter in the tray  530  so as to keep the cat litter at a constant level. At its furthest point across the tray  530 , the bottom wall  555  may form a berm of cat litter at the front of the tray  530 . When the tray  530  is later pivoted over the return bin  530 , the berm will be the first to fall out of the tray  530 , thereby coating any unburied cat waste prior to said waste being dumped into the filter  570 . This minimizes sticking of the cat waste to the filter  570 , thereby preventing clogs and lengthening the useful life of the filter  570 . 
         [0106]      FIG. 26  is a partially cut away perspective view of a cat litter box, generally designated by reference number  700 , according to an exemplary embodiment of the present invention. The cat litter box  700  has generally the same construction as that of the previous embodiment, except for the added feature of a moveable cover. In this regard, the cat litter box  700  may include a cover  710 , a cover drive system  810 , a base frame similar to the base frame  520 , a cat litter tray  730  similar to the cat litter tray  530 , a cat litter tray drive system similar to the cat litter tray drive system  540 , a cat litter return bin similar to the cat litter return bin  550 , a cat litter return bin drive system similar to the cat litter return bin drive system  560 , a cat litter filter  770  similar to the cat litter filter  570 , a waste bin  780  similar to the waste bin  580 , a hopper similar to the hopper  590 , and a cat litter return bin transport drive system  800  similar to the cat litter return bin transport drive system  600 . 
         [0107]      FIG. 27  is a perspective view of the cover drive system  810  according to an exemplary embodiment of the present invention. The cover drive system  810  may include a motor (not shown) that rotates screw drives  812  through a drive train  814 , such as, for example, a drive chain and sprocket gears. The cover drive system  810  may also include a drive wall  816  having threaded collars  818  through which the screw drives  812  pass so that rotation of the screw drives  812  causes the drive wall  816  to move back and forth depending on the direction of rotation. 
         [0108]      FIG. 28  is a partially cut away perspective view of the cat litter box  700  in a configuration that appears similar to a conventional covered cat litter box. The cover  710  may include a front cover component  712  and a back cover component  714 , with the front cover component  712  being slideable relative to the back cover component  714 . In the configuration shown in  FIG. 28 , the front cover component  712  has been pushed forward and the drive wall  816  has been driven to a position substantially in the back of the cat litter box  700  so that the cat litter box  700  may function as a covered box. In this regard, the cover  710  may include a door  716  attached to the drive wall  816 . In the configuration shown in  FIG. 28 , the door  716  is in an open position to allow a cat to enter the cat litter box  700 . The position of the door  716  in the open position also prevents the cat from gaining access to components at the back of the cat litter box  700  so that the cat can not cause damage to the components or injure himself. The front cover component  712  may be locked in the forward position by any suitable locking mechanism  718 , such as, for example, one or more clamps. 
         [0109]    At the beginning of a cleaning cycle, it is important that a cat within the cat litter box  700  is forced to vacate and that no other cats are allowed to enter so that the cat does not get injured. Thus, as shown in  FIG. 29 , the cover drive system  810  may be activated at the beginning of a cleaning cycle to push the drive wall  816  towards the front of the cat litter box  700 , which in turn moves the door  716  in position to seal the cat litter box  700 . The forward movement of the door  716  forces a cat in the cat litter box  700  to vacate and the sealing of the door  716  prevents entry. 
         [0110]    If a user chooses to operate the cat litter box  700  as a conventional box without a cover, the user may push the front cover component  712  back into contact with the door  716 , as shown in  FIG. 26 . The front cover component  712  may then be locked to the door  716  by a locking mechanism  720 , such as, for example, one or more clamps, so that the front cover component  712  will follow the movement of the drive wall  816 . For example, at the beginning of a cleaning cycle the drive wall  816  may be driven forward, which results in sealing of the cat litter box  700  by the front cover component  712  and door  716 . At the end of the cleaning cycle, the drive wall  816  may be driven backwards, thereby pulling the door  716  and attached front cover component  712  back into an open configuration. 
         [0111]    Now that exemplary embodiments of the present invention have been shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art.