Patent Publication Number: US-6707030-B1

Title: System and method of automatic dynamic calibration for infrared sensing device

Description:
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/267,441 entitled, “Remotely Managed Automatic Dispensing Apparatus and Method”, filed on Feb. 8, 2001, and U.S. Provisional Patent Application Ser. No. 60/242,898 entitled, “Remotely Managed Automatic Dispensing Apparatus and Method”, filed on Oct. 24, 2000, the entireties of which are incorporated herein by reference. 
    
    
     BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates generally to the field of infrared detecting devices and more particularly to the automatic standardized calibration of infrared detection devices. 
     2. Technical Background 
     Various methods have been employed to electronically control water flow through a water control device such as a faucet or spigot. Among the accepted and conventional methods is the use of an optical sensor for detecting reflections from an infrared (‘IR’) source or IR emitter. Generally speaking, a pulsed IR beam is reflected from an object (such as a user&#39;s hands) and sensed to determine whether to activate or deactivate a solenoid valve to control water flow from the water control device. When processing electronics determine the reflection has exceeded a threshold value, a control signal opens a solenoid valve. Pulsed IR sensing remains at the forefront of sensing techniques used with these types of devices due in part to its reasonable performance and low cost. 
     Because of variations in processing circuits, emitter characteristics and sensor chaeristics, it is necessary to calibrate an IR system. Calibration of infrared sent devices such as, for example, automatically activated flow control devices is labor intensive and inefficient with respect to devices presently on the market. The low cost IR sensing devices employed in automatically activated flow control devices vary with respect to power requirements, performance, and other criteria. As a result, readings taken by these IR sensing devices (such as whether a user&#39;s hands are present beneath the aerator of a faucet) are generally non-uniform from device to device, and therefore often result in improper activation and deactivation of some devices. Similarly, as battery power for these devices decreases over time, so does the power output of the IR sensing devices. Moreover, water droplets sprayed or otherwise deposited on or near a lens or lens cover of an IR sensing device have been known to cause the IR sensing devices to malfunction. As a result, manual calibration of conventional IR sensing devices of automatically activated flow control devices is generally required on a frequent basis following extended periods of use. The repeated manual calibration can be time consuming and costly, particularly when the IR s g devices are located in areas that are difficult to access. 
     SUMMARY OF INVENTION 
     The present invention generally provides a system and method for calibrating infrared detecting devices, which detect the presence of objects by detecting IR reflections. A system in accordance with an exemplary embodiment of the present invention includes calibrating the output of the IR detector by a control module, which receives the output of the IR detector and regulates the input of the IR emitter. The method e or reduces the need to manually calibrate and adjust each IR detector and IR emitter that is part of the infrared detecting device. The control module repeatedly activates the IR emitter with an input value to emit IR radiation, which is reflected from an object in the surrounding environment to the IR detector. The output from the IR detector is transmitted to a control module. If the IR detector output is not within a standard range of values for randomly reflected infrared radiation, a calibration manager increases or decreases the input to the IR emitter. This process is repeated until the output of the IR detector is within the standard range of values. The value of the corresponding input to the IR emitter to maintain this value of the IR detector within the standard range of values is stored in the nonvolatile memory of the control module and the calibration manager reprograms itself to use this calibration value of input to the IR emitter as a reference standard. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram illustrating a fluid dispensing system in accordance with an examplary embodiment of the present invention. 
     FIG. 2 is a block diagram illustrating a more detailed view of the fluid dispensing system depicted in FIG.  1 . 
     FIG. 3 is a flow chart illustrating the architecture and functionality of an infrared dynamic calibration system depicted in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the following description details the preferred embodiments of the present invention, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of the parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced in various ways. 
     FIGS. 1 and 2 show a fluid dispensing system  8  that employs an infrared detection system  9  in accordance with the present invention As shown in FIG. 1, the fluid dispensing system  8  includes an automated faucet  10  having an aerator  7  from which fluid (e.g., water) is dispensed. Automated faucet  10  has plumbing  11  in line with a solenoid valve  12  and a mixing valve  13 , which is connected to a hot water source  14  and a cold water source  15 . Faucet  10  also has IR emitter  16  and IR detector  17  on a sensor board  22  in a collar  18  of the faucet  10 . The sensor board  22  is preferably connected electrically to a control module  19  a by connector  20 . The connector  20  provides power to sensor board  22  and control module  19 . Control module  19  may also be connected electrically to solenoid  12  by connector  21 . 
     In the example shown by FIG. 1 a calibration manager  38  (see FIG. 2) in control module  19  controls the intensity and duration of each pulse emitted from IR emitter  16 . When a user places his or her hands near faucet  10  (e.g., underneath aerator  7 ), the emitted IR pulse is reflected from the hands to IR detector  17 . IR detector  17  provides an output value indicative of the amount of the amplitude of the detected pulse and a solenoid controls the op on of the solenoid valve  12  based on the IR detector&#39;s output value. More specifically, the solenoid controller  40  compares the output value to a threshold value stored in memory  35 , and will open solenoid valve  12  if the output value exceeds the stored threshold value. 
     To insure proper operation during use it is desirable to calibrate the IR emitter  16  and IR detector  17 . In accordance with the present invention, calibration is performed automatically by the calibration manager  38 . 
     FIG. 2 shows the components of an infrared detecting device used in the calibration procedure for the present invention. Sensor board  22  has IR emitter  16  and IR detector  17 , which are connected to IR emitter amp  30  and IR detector amp  31 , respectively. Control module  19  has a power supply  33 , which receives power from batteries  32  and provides power to a signal processor  34 , memory  35 , a solenoid power source  36 , and a solenoid switch  37 . The calibration manager  38  and solenoid controller  40  can be implemented in hardware, software, or a combination thereof. In the preferred embodiment, as shown by FIG. 2, the calibration manager  38  and solenoid controller  40  are implemented in software and stored within memory  35 . During operation, the signal processor  34  executes the calibration manager  38  and solenoid controller  40 . Note that the signal processor  34  can be any known processing element for executing instructions of software programs. 
     The solenoid switch  37  under the control of solenoid controller  40 , can open and close solenoid valve  12 . If desired, control module  19  may communicate with a remote computer  41  so that computer  41  can remotely monitor the memory  35  and calibration values obtained during a calibration procedure that will be described in more detail hereafter. Computer  41  may be adapted to use any known operating system and may comprise a processor, random access memory, read only memory, disk drives, display, communications applications, and the like. The values of inputs to the IR emitter  16  and outputs from the IR detector  17  will have optimal or standard ranges in which the infrared detecting device can operate satisfactorily. The minimum end of the range has values below which the fluid dispensing system  8  may not detect a user, and the high end of the range has values above which the fluid dispensing system  8  may falsely detect a user. These maximum and minimum output ranges and the midpoint of these output ranges can be stored in memory  35  as part of the calibration data  39 . The infrared detection and calibration system  9  includes sensor board  22 , memory  35 , and signal processor  34 . 
     Calibration manager  38  is configured to send an appropriate input signal to IR emitter amp to cause IR emitter  16  to emit a pulse of infrared radiation. The amplitude of such a pulse is preferably based on the value or strength of the input signal. The emitted radiation, when reflected by an object in the surrounding environment, is detected by IR detector  17 , and an output signal is thereby sent to IR detector amp  31 , which then sends an amplified output signal to signal processor  34 . Calibration manager  38  is configured to evaluate this output signal based on the standard range of values contained in calibration data  39  and to calibrate the emitter based on such evaluation. 
     In some cases, IR detector output may be too high because randomly reflected emitted IR radiation is too high. Randomly reflected emitted radiation is emitted radiation that is reflected back to the detector by an object other than a user. As an example, randomly reflected emitted radiation may include radiation reflected from a sink wall. The output signal of the IR detector  17  may, thus, falsely indicate the presence of a user when a significant amount of emitted IR radiation is randomly reflected. If randomly reflected emitted IR radiation is too high, control module  19  can provide an input signal to IR emitter amp  30  to decrease input to IR emitter  16  incrementally as desired, thereby decreasing randomly reflected emitted IR radiation to a desired level. In other cases, the lenses in collar  18  may have a deposit of film or dirt on them so that relatively little randomly reflected emitted IR radiation is detected. Control module  19  can then provide an input signal to IR emitter amp  30  to increase input to IR emitter  16  incrementally as desired, thereby increasing randomly reflected emitted IR radiation to a desired level. The calibration correction tests can be conducted, for example, after every on/off cycle of the solenoid valve  12  or when a quiet period has occurred for a defined period of time. 
     The dynamic calibration method of the present invention for IR detecting devices in commercial use is shown in FIG.  3 . Control module  19  first tests for IR detector  17  output in response to randomly reflected emitted IR radiation (step  60 ) which is continuously generated by pulses of emitted infrared radiation in the absence of the user&#39;s hands. Calibration manager  38  then determines whether this output in response to detected randomly reflected emitted IR radiation is too high or too low compared to a maximum and minimum range of standard output values contained in calibration data  39  (step  61 ). If the IR detector  17  output exceeds the maximum of the standard range, calibration manager  38  provides an input signal to IR emitter  16  whereby IR emitter  16  produces an infrared signal or pulse (IR radiation) having a reduced amplitude (Step  62 ) if IR emitter  16  output is not already at a minimum (step  63 ). If IR emitter output is not at a minimum of the standard to IR emitter  16  is lowered incrementally by calibration manager  38  (step  64 ). The cycle is repeated (step  60 ) until detected randomly reflected IR emitter radiation is maintained within the range of standard values. The corresponding input value to the IR emitter  16  is stored in calibration manager  38  of control module  19  as a calibration standard until the next calibration. If IR emitter output is already at minimum, the IR detecting device may be considered defective or inoperable and any suitable indicator can be signaled by control module  19  (step  65 ). 
     If randomly reflected emitted IR radiation is too low, calibration manager  38  will then provide an input signal to IR emitter  16  to increase its IR radiation output (step  66 ) only if IR emitter  16  output is not already at a maximum (step  67 ). If IR emitter output is not at a maximum, then the input value to IR emitter  16  is increased incrementally (step  68 ), and the cycle is repeated (step  60 ) until detected randomly reflected IR emitter radiation is maintained within the range of standard values. The corresponding input value to the IR emitter  16  is stored in calibration manager  38  of control module  19  as a calibration standard until the next calibration. If IR emitter output is already at a maximum, the IR detecting device may be considered defective or inoperable and any suitable indicator can be signaled by control module  19  (step  69 ). 
     During use of the IR sensing device, the power output of batteries  32  may decline with time such that IR radiation output from IR emitter  16  may decline with time, resulting in decreased IR detector output. If randomly reflected emitted IR radiation is neither too high nor too low, compared to the standard range of values, calibration manager  38  may make adjustments to IR emitter input to compensate for a change in battery and power supply output by increasing input to IR emitter  16 . This adjustment to IR emitter input may be made relative to a minimum and maximum range of standard values for IR emitter input values stored in calibration data  39  (step  70 ). The calibration test is then complete (step  71 ). The calibration process can be performed as frequently as desired, preferably every 0.25 seconds, for ambient lighting and change in battery output. 
     It is apparent from the above description of the calibration method of the present invention that control module  19  calibrates itself rather than making changes directly to the IR emitter and IR detector assembly (collar  18 ) that is associated with it. Thus, the collars  18  need no direct calibration and any collar can substitute for any other collar. In use, after replacing a collar with a new collar, or after unplugging and plugging in a collar, the fluid dispensing system  8  will automatically calibrate the new collar without any need for manual calibration. Thus, the method of the present invention greatly facilitates the maintenance of infrared detection devices. 
     The foregoing description has been limited to specific embodiments of this invention. It will be apparent, however, that variations and modifications may be made by those skilled in the art to the disclosed embodiments of the invention, with the attainment of some or all of its advantages and without departing from the spirit and scope of the present invention. For example, inputs to IR emitter  16  or outputs from IR detector  17  may be measured in current or voltage. Various types of IR emitters and/or detectors may be employed to implement the IR emitter  16  and or the IR detector  17  of the present invention. Collar  18  may have other structural features contained therein, such as a microprocessor or an IRDA photodiode for diagnostic and maintenance functions, or a power supply and power source. Control module  19  may have any suitable type of microprocessor or computer to perform programing, software implementation, and data storage and memory. The control module  19  may use an AC source of power instead of batteries. 
     It will be understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated above in order to air the nature of this invention may be made by those skilled in the art without departing from the principle and scope of the invention as recited in the following claims.