A plumbing device uses electronic control circuitry with two infrared emitters and one infrared receiver to detect objects in a particular region of space. In one embodiment, detection of an object using both sensors (in sequential scans) results in the plumbing device turning on. When no object has been detected for a certain amount of time, the plumbing device is turned off. Also, when the plumbing device has run for another certain amount of time, the plumbing device is turned off regardless of whether an object is still being detected. In another embodiment, the output of the IR emitters is partially blocked by one or more mask elements to tailor the region that is covered by both IR emitters and, hence, the region that triggers the opening of the plumbing device valve.

BACKGROUND OF THE INVENTION 
     The present invention relates controls for plumbing devices, and more particularly to plumbing devices automatically triggered by infrared-based object detection. 
     Object detection systems that use infrared (IR) signals to trigger plumbing device operation, such as operation of an automatic faucet, are known. Typically, these systems utilize a single IR emitter and an IR detector to control fluid flow based upon object detection within a defined region. A control activates the IR emitter and then monitors the IR detector for reflections of infrared light from objects (such as a user's hands) that are sensed and used to determine whether to activate or deactivate a solenoid valve. 
     The object detection systems are typically designed and implemented integral to the plumbing device. Disadvantageously, this may result in the failure of the plumbing device to trigger operation until the user's hand is directly under the faucet. The object detection systems also are prone to false triggering as a result of unwanted reflections off of surrounding objects, such as a sink, or off the water stream itself. If the reflection off the water stream is not avoided, the solenoid valve may become locked-on, thus resulting in a waste of water and annoyance to the user. 
     Accordingly, it is desirable to provide an improved automatic plumbing device that provides a more tailored detection area and reduces false triggering caused by reflections. 
     SUMMARY OF THE INVENTION 
     An automatic plumbing device according to the present invention provides improved object detection in a desired volume. 
     The automatic plumbing device of the present invention includes a first IR emitter, a second IR emitter and an IR receiver mounted within a plumbing body. The two IR emitters and the IR receiver are configured so that objects in a sensitivity volume are detected. A controller manages the detection process and controls the operation of the IR emitters in sequence to yield emissions within a first region of sensitivity and a second region of sensitivity. Based on emitted returns received through the IR receiver from the first region of sensitivity and the second region of sensitivity, the controller opens or closes a valve using a solenoid control. In some forms of the invention, the first region of sensitivity and the second region of sensitivity are more narrowly tailored by a first and second mask. 
     Delay circuitry may allow water to flow for a period of time after the last object is detected, and limits the total length of time that water can constantly run. A voltage regulator and low battery detector detects whether the power being supplied to the circuit is adequate (e.g., above a certain threshold voltage). 
     The invention may be used as part of a faucet, although other plumbing applications are within the scope of this invention. 
     The automatic plumbing device according to the present invention provides a more tailored detection region and reduces false triggering of the device caused by reflections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  is a perspective view of a water faucet incorporating an object detection system according to the present invention; 
         FIG. 2  is a plan view of the detection fields of emitters configured according to one embodiment of the present invention; 
         FIG. 3  is a block diagram of the object detection system according to the present invention; 
         FIG. 4  is a flow chart describing the logical progression of tests and events in one embodiment of the present invention; and 
         FIG. 5  is a plan view of the detection fields of emitters configured according to a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , a water faucet  10  adapted with an object detection system  12  according to the present invention is illustrated. Although the object detection system  12  is shown and described in terms of a water faucet  10 , it should be understood that other plumbing devices, including but not limited to toilets and showers, may employ the configuration disclosed herein. 
     The water faucet  10  defines a spout section  11  and a base section  14 . The base section  14  includes a housing  16  for housing the object detection system  12  of the present invention. A pipe  17  communicates a liquid, such as water, through the base section  14  to the spout section  11  where the water exits the water faucet  10 . 
     Referring to  FIG. 2 , the configuration of the object detection system  12  within the housing  16  of the water faucet  10  is illustrated. The housing  16  houses an IR emitter  18  (on the top as shown in  FIG. 2 ), an IR emitter  20  (on the bottom), and an IR receiver  22  (in the center) as shown. Each IR emitter  18  and  20  is oriented so its region of sensitivity is limited by a mask ( 26  and  28 , respectively). These masks limit the zones of sensitivity of the IR emitter  18  and the IR emitter  20  to a first region of sensitivity  30  and a second region of sensitivity  32 , respectively. An overlap of the first region of sensitivity  30  and the second region of sensitivity  32  defines a sensitivity volume  34  having a starting point  33  and an endpoint  35 . As shown in  FIG. 2 , the IR emitters  18 ,  20  are oriented towards each other such that the first region of sensitivity  30  and the second region of sensitivity  32  intersect at the starting point  33  and diverge at the endpoint  35 . More particularly, the first region of sensitivity  30  includes an inner boundary  30 A and a diverging outer boundary  30 B, while the second region of sensitivity  32  includes an inner boundary  32 A and a diverging outer boundary  32 B. The intersection of the inner boundaries  30 A and  32 A define the starting point  33  of the sensitivity volume  34 . Likewise, the intersection of the outer boundaries  30 B and  32 B define the endpoint  35  of the sensitivity volume  34 . As shown in  FIG. 2 , a first portion of the sensitivity volume  34  is defined by the inner boundaries  30 A and  32 A, while a second portion of the sensitivity volume  34  is defined by the outer boundaries  30 B and  32 B. The sensitivity volume  34  is the region on which objects will be detected as described below. It can be seen from  FIG. 2  that the location, shape, and size of the sensitivity volume  34  can be modified by manipulating the location and orientation of the IR emitters  18  and  20 , the IR receiver  22 , and the masks  26  and  28 , as would occur to one skilled in the art. As shown in  FIGS. 1 and 2 , the IR emitters  18 ,  20  in this example are disposed in substantially the same horizontal plane. 
     Referring to  FIG. 3 , using logic to apply a method that will be described below, a controller  36  communicates with a memory  38  that contains instructions executable by the controller  36  to perform the control process. The controller  36  may be of any suitable microcontroller, microprocessor, computer or the like that would occur to one skilled in the art. The memory  38  may include a hard drive, CD-ROM, DVD, RAM, ROM or other optically readable storage, magnetic storage, or integrated circuit. 
     The controller  36  selectively and periodically activates the IR emitter  18  and the IR emitter  20  to cause returns to be received at the IR receiver  22 . The levels of these returns vary depending on whether an object is present within the sensitivity volume  34 . A filter/amplifier  40  conditions the signal from the IR receiver  22  and provides it to a comparator  42 . The comparator  42  compares the filtered and amplified signal from the filter/amplifier  40  to a threshold provided by the controller  36  to provide a comparison output to controller  36 . The controller  36  applies the logic and method described below to actuate a solenoid control  44 , which turns the associated plumbing device on and off when appropriate. Power to the controller  36 , such as by one or more dry cells (not shown), is monitored by a voltage regulator/low battery detector  46 . If the voltage regulator/low battery detector  46  indicates a power problem, or if another error condition is indicated, the controller  36  activates a status alert  48  to notify a user or maintenance worker of the problem. 
     Referring to  FIG. 4 , with continuing reference to  FIGS. 1 ,  2  and  3 , the operation of the object detection system  12  will now be discussed. Procedure  100  begins at start point  101  when power is applied to the system. The controller  36  waits at block  110  while power is established and stabilized. The system initializes at block  120  by forcing the solenoid control  44  to an “off” position and calibrating the IR emitters  18  and  20 , the IR receiver  22 , the filter/amplifier  40 , and the threshold value provided by the controller  36  to the comparator  42 , as would be understood by those skilled in the art. 
     The system determines at decision block  130  whether a faucet valve is in an “on” position. If so, a watchdog timer (implemented using the controller  36  or other means as would occur to one skilled in the art) is updated at block  133 . If the updated watchdog timer reflects that the faucet valve has been on more than a predetermined amount of time (thirty seconds, for example), as determined at decision block  135 , the microcontroller  36  closes the faucet valve using the solenoid control  44  and sets the watch dog timer (“WDT”) flag, these steps being combined at block  137 . Then, or following a negative result at block  135 , or upon a negative result of block  130 , the system proceeds to decision block  140 . 
     At decision block  140 , the controller  36  checks its input from the voltage regulator/low battery detector  46  to determine whether the power supply is low. If so, the controller  36  executes a power monitor and status routine at block  145  and returns to decision block  130 . This routine determines whether to initiate low-power-consumption measures; set an audio, visual, or other alarm; and/or take other action as would occur to one skilled in the art. 
     Upon a negative result at decision block  140 , the controller  36  refreshes the sensor reference voltage at block  150  using one or more techniques that would occur to one skilled in the art. The controller  36  then runs a detection test at block  160 . In doing so, the elements of system  100  cooperate to “ping” the faucet environment using the IR emitter  18  and receive the result using the IR receiver  22 . The controller  36  then pauses to allow the system to settle and verify that the IR return being received has returned to a nominal level. The system then emits a ping using the IR emitter  20  and reads the return using the IR receiver  22 , then pauses to allow the system to settle again and verify once more that the IR return has dropped to a nominal level. 
     Then, at decision block  170 , the system evaluates whether an object has been detected in the sensitivity volume  34  by comparing the returns received at the IR receiver  22  during the detection test at decision block  160  to a threshold value provided by the controller  36 . The threshold value is a stored return level value representing what the return level value would be (plus or minus a range of error) in the event an object, such as a hand, is within the sensitivity volume  34 . The threshold value must be detected during the first ping and the second ping of the detection test at decision block  160  before the controller  36  recognizes an object within the sensitivity volume  34 . If an object has been detected at decision block  170 , the system determines at decision block  172  whether the WDT flag is set. After a negative result at decision block  172 , the system returns to decision block  130 . 
     If the result of decision block  172  is positive (i.e., the WDT flag is reset), the system determines (using the solenoid control  44  or an internal copy of its state) whether the faucet valve is in an “on” position. If so, the “off delay timer” is reset at block  176 , and the system returns to decision block  130 . If, however, the result of decision block  174  is negative (i.e., the faucet valve is off), the system turns on the faucet valve and sets the ON flag at block  178 . The system then returns to decision block  130 . 
     If there is a negative result at decision block  170  (i.e., one or both pings at decision block  160  produced negative results), the WDT flag is reset at block  180 . The system then tests the ON flag to determine at block  190  whether the faucet valve is on. If not, the system returns to decision block  130 . 
     If the faucet valve is on (i.e., there is a positive result at decision block  190 ), the off delay timer is updated at block  192 . The off delay timer is tested at decision block  194  to determine whether it reflects a period greater than a predetermined length of time (e.g., two seconds). If the time is less than the predetermined amount (negative result at block  194 ), the system returns to decision block  130 . Otherwise (positive result at block  194 ) the faucet valve is turned off and the flags are reset at block  196 , then the system returns to decision block  130 . 
     An alternative embodiment of the present invention is shown in  FIG. 5 . Here, the IR emitter  18 , the IR emitter  20 , and the IR receiver  22  are positioned and oriented in much the same way as in the embodiment shown in  FIG. 2 . In this alternative embodiment, however, no masks are used to shape the emissions from the IR emitters  18  and  20 . Instead, the positioning and orientation of those components are more precisely tailored to yield a first region of sensitivity  50  and a second region of sensitivity  52 . The overlap of the first region of sensitivity  50  and the second region of sensitivity  52  defines a sensitivity volume  54 . The same logic and method can be used to control this embodiment as was described in relation to  FIGS. 3 and 4 . 
     While IR emitters have been disclosed, other emitters capable of creating a deflected signal may be utilized within this invention. 
     That the foregoing description shall be interpreted as illustrative and not in a limiting sense is thus made apparent. A worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claim should be studied to determine the true scope and content of this invention.